Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus

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SCERT Class 8 Maths Chapter 3 Solutions Square Identities

Class 8 Kerala Syllabus Maths Solutions Chapter 3 Square Identities Questions and Answers

Square Identities Class 8 Questions and Answers Kerala Syllabus

Squares of Sums (Page No. 40)

Question 1.
Calculate the squares below in your head:
(i) 152
(ii) 252
(iii) 332
(iv) \(\left(5 \frac{1}{2}\right)^2\)
(v) \(\left(10 \frac{1}{2}\right)^2\)
(vi) \(\left(25 \frac{1}{2}\right)^2\)
(vii) \(\left(5 \frac{1}{5}\right)^2\)
Answer:
(i) 152 = 102 + 52 + 2 × 10 × 5 = 225
(ii) 252 = 202 + 52 + 2 × 20 × 5 = 625
(iii) 332 = 302 + 32 + 2 × 30 × 3 = 1089
(iv) \(5 \frac{1^2}{2}=5^2+5+\frac{1}{2^2}=30 \frac{1}{4}\)
(v) \(10 \frac{1}{2}^2=10^2+10+\frac{1}{2^2}=110 \frac{1}{4}\)
(vi) \(25 \frac{1}{2}^2=25^2+25+\frac{1}{2^2}=650 \frac{1}{4}\)
(vii) \(5 \frac{1}{5}^2=5^2+2+\frac{1}{5^2}=27 \frac{1}{25}\)

Question 2.
In the general identity on the square of a sum of two numbers, what special case do we get by taking one of the numbers as 2? Do the calculations below in your head, using this:
(i) What is 222?
(ii) What is 522?
(iii) 252 = 625; What is 272?
Answer:
(x + 1)2 = x2 + 2 × x × 2 + 22 = x2 + 4x + 4
(i) 222 = (20 + 2)2
= 202 + 2 × 20 × 2 + 22
= 400 + 80 + 4
= 484

(ii) 522 = (50 + 2)2
= 502 + 2 × 50 × 2 + 22
= 2500 + 200 + 4
= 2704

(iii) 252 = 625
272 = (25 + 2)2
= 252 + 2 × 25 × 2 + 22
= 625 + 100 + 4
= 729

Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus

Question 3.
432 = 1849
(i) What is 442?
(ii) What is 462?
Answer:
432 = 1849
(i) 442 = (43 + 1)2
= 432 + 2 × 43 × 1 + 12
= 1849 + 86 + 1
= 1936

(ii) 462 = (43 + 3)2
= 432 + 2 × 43 × 3 + 32
= 1849 + 258 + 9
= 2116

Textbook Page No. 45

Question 1.
Calculate the squares of some odd numbers and check the following statement. Explain why they are true:
(i) The square of any odd number is odd.
(ii) The square of any odd number leaves a remainder of 1 on division by 4.
(iii) The square of any odd number leaves a remainder of 1 on division by 8.
Answer:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Page 45 Q1
(i) Let the odd number be, 2n + 1 where n = 0, 1, 2, 3,…..
(2n + 1)2 = 4n2 + 4n + 1 = 2(2n2 + 2n) + 1
∴ The square of an odd number is of the form 2n + 1, which is an odd number.

(ii) (2n + 1)2 = 4n2 + 4n + 1 = 4(n2 + n) + 1
That means the square of an odd number is 1 more than a multiple of 4.
∴ It leaves a remainder of 1 on division by 4.

(iii) (2n + 1)2 = 4n(n + 1) + 1
Among the two consecutive numbers n and n + 1, one is always even.
So n(n + 1) is always even.
Thus, 4n(n + 1) is divisible by 8.
Hence, the square is of the form multiple of 8 + 1.
That means it leaves a remainder of 1 on division by 8.

Question 2.
Calculate the remainders on dividing the squares of some natural numbers by 4. Explain why the Statements below are true:
(i) The square of any natural number divided by 4 leaves a remainder of 0 or 1.
(ii) Any natural number that leaves a remainder of 2 or 3 on division by 4 is not a perfect square.
Answer:
The natural numbers on division by 4 are of the form 4n, 4n + 1, 4n + 2, 4n + 3, where n = 0, 1, 2,…
The possible remainders are 0, 1, 2, 3.
(i) Even natural numbers can be written as 2n
Squaring it gives (2n)2 = 4n2
Here, the remainder is 0.
Odd natural numbers can be written as 2n + 1
Squaring it gives,
(2n + 1)2 = 4n2 + 4n + 1 = 4(n2 + n) + 1
Here, the remainder is 1.
∴ The square of any natural number divided by 4 leaves a remainder of 0 or 1.

(ii) The square of any natural number divided by 4 leaves a remainder of 0 or 1.
∴ Any natural number leaving a remainder of 2 or 3 when divided by 4 is not a perfect square.

Question 3.
See this pattern:
3 = 22 – 12
5 = 32 – 22
7 = 42 – 32
Check whether some other odd numbers can also be written as the difference of two perfect squares. Explain why all odd numbers greater than 1 can be written like this.
(Hint: Recall the general form of an odd number seen in class 7).
Answer:
All odd numbers greater than 1 can be written as the difference of two perfect squares.
Specifically, the difference of the squares of two consecutive natural numbers.
That is, (n + 1)2 – n2 = 2n + 1, always an odd number.
So, for any odd number n, it can be written as (n + 1)2 – n2.

Question 4.
Give reasons for the fact that the square of any number ending in 1 also ends in 1. What about numbers ending in 5? And numbers ending in 6?
Answer:
The last digit of a square is determined by the last digit of the original number.
The numbers ending in 1, 5, or 6 will have squares ending in 1, 5, or 6, respectively.
Because their last digits, when multiplied by themselves, result in the same digit.

Squares of Differences (Page No. 50)

Question 1.
Calculate the squares below in your head:
(i) 292
(ii) 382
(iii) 9992
(iv) \(\left(9 \frac{1}{2}\right)^2\)
(v) (9.7)2
Answer:
(i) 292 = (30 – 1)2
= 302 – 2 × 30 × 1 + 12
= 900 – 60 + 1
= 841

(ii) 382 = (40 – 2)2
= 402 – 2 × 40 × 2 + 22
= 1600 – 160 + 4
= 1444

(iii) 9992 = (1000 – 1)2
= 1000000 – 2000 + 1
= 998001

(iv) \(\left(9 \frac{1}{2}\right)^2=9 \times 10+\frac{1}{4}=90 \frac{1}{4}\)
Or
\(\left(9 \frac{1}{2}\right)^2=\left(10-\frac{1}{2}\right)^2=10^2+\left(\frac{1}{2}\right)^2-10=90 \frac{1}{4}\)

(v) (9.7)2 = (10 – 0.3)2
= 102 + (0.3)2 – 2 × 10 × 0.3
= 100 + 0.09 – 6
= 94.09

Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus

Question 2.
See these computations:
32 – (2 × 3) = 3 = 22 – 1
42 – (2 × 4) = 8 = 32 – 1
52 – (2 × 5) = 15 = 42 – 1
Explain the general principle of these using algebra.
Answer:
32 – (2 × 3) = 3 = 22 – 1
42 – (2 × 4) = 8 = 32 – 1
52 – (2 × 5) = 15 = 42 – 1
…………………………………..
…………………………………..
n2 – (2 × n) = (n – 1)2 – 1

Textbook Page No. 53, 54

Question 1.
See these computations:
\(\left(\frac{1}{2}\right)^2+\left(1 \frac{1}{2}\right)^2=2 \frac{1}{2}\); 2 = 2 × 12
\(\left(1 \frac{1}{2}\right)^2+\left(2 \frac{1}{2}\right)^2=8 \frac{1}{2}\); 8 = 2 × 22
\(\left(2 \frac{1}{2}\right)^2+\left(3 \frac{1}{2}\right)^2=18 \frac{1}{2}\); 18 = 2 × 32
(i) Write the next two lines following this pattern.
(ii) Explain the general principle of these using algebra.
Answer:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Page 53 Q1

Question 2.
Some natural numbers can be written as the difference of two perfect squares in two different ways. For example
24 = 72 – 52 = 52 – 12
32 = 92 – 72 = 62 – 22
40 = 112 – 92 = 72 – 32
Write the next few multiples of 8 as the difference of two perfect squares in two different ways. Explain algebraically how we can do this for all multiples of 8 starting with 24.
Answer:
The next few lines are:
48 = 132 – 112 = 82 – 42
56 = 152 – 132 = 92 – 52
64 = 172 – 152 = 102 – 62
Algebraic explanation is: 8x = (2x + 1)2 – (2x – 1)2 where x is 3, 4, 5,……….

Question 3.
See how some numbers are written as the difference of two perfect squares in two different ways:
15 = 82 – 72 = 42 – 12
21 = 112 – 102 = 52 – 22
35 = 182 – 172 = 62 – 12
(i) What are the different ways in which the numbers 15, 21, and 35 can be written as the product of two factors?
(ii) Find two more numbers of this type, which can be written as the difference of two perfect squares in two different ways.
(iii) What general result can we form from this?
Answer:
(i) 15 = (8 – 7) × (8 + 7) = 1 × 15
15 = (4 – 1) × (4 + 1) = 3 × 5
21 = (11 – 10) × (11 + 10) = 1 × 21
21 = (5 – 2) × (5 + 2) = 3 × 7
35 = (18 – 17) × (18 + 17) = 1 × 35
35 = (6 – 1) × (6 + 1) = 5 × 7

(ii) 45 = 92 – 62 = 72 – 22
65 = 332 – 322 = 92 – 42

(iii) a2 – b2 = (a – b)(a + b)

Question 4.
Compute the following products by writing them as the difference of two squares.
(i) 78 × 22
(ii) 301 × 299
(iii) \(2 \frac{1}{3} \times 1 \frac{2}{3}\)
(iv) 10.7 × 9.3
Answer:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Page 53 Q4

Question 5.
Find the largest of each of the following pairs of products, without actual multiplication:
(i) 75 × 25; 76 × 24
(ii) 76 × 24; 74 × 26
(iii) 10.6 × 9.4; 10.4 × 9.6
Answer:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Page 53 Q5

Differences of Squares (Page No. 58, 59, 60)

Question 1.
Do the computations below in your head:
(i) 682 – 322
(ii) \(\left(3 \frac{1}{2}\right)^2-\left(2 \frac{1}{2}\right)^2\)
(iii) 3.62 – 1.42
Answer:
(i) 682 – 322 = (68 – 32)(68 + 32)
= 36 × 100
= 3600

(ii) \(\left(3 \frac{1}{2}\right)^2-\left(2 \frac{1}{2}\right)^2=\left(\frac{7}{2}\right)^2-\left(\frac{5}{2}\right)^2=\left(\frac{7-5}{2}\right)\left(\frac{7+5}{2}\right)\)
= 1 × 6
= 6

(iii) 3.62 – 1.42 = (3. 6 – 1.4)(3.6 + 1.4) = 11

Question 2.
Note the pattern in the computations below:
32 – 22 = 5 = 3 + 2
42 – 32 = 7 = 4 + 3
52 – 42 = 9 = 5 + 4
(i) Write the next two computations following these.
(ii) Write the general principle in these as an algebraic equation.
(iii) Write this general principle in ordinary language.
Answer:
(i) 62 – 52 = 11 = 6 + 5
72 – 62 = 13 = 7 + 6

(ii) n2 – (n – 1)2 = 2n – 1 = n + (n – 1)

(iii) The difference between the square of an integer and the square of the preceding integer is equal to the sum of those two integers.

Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus

Question 3.
In a calendar sheet, take a square containing nine numbers and mark the numbers on the left and right, top, and bottom of the middle number:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Page 58 Q3
Calculate the products of the left and right numbers and the top and bottom numbers, and also their difference
8 × 10 = 80
2 × 16 = 32
80 – 32 = 48
Do this for other squares of nine numbers. Explain using algebra why the difference is 48 in all cases.
(Hint: It is convenient to take the middle number as x)
Answer:
Let the middle number be x.
The number to the left is x – 1.
The number to the right is x + 1.
The number on top is x – 7.
The number on the bottom is x + 7.
Since, in a calendar, the numbers in a row differ by 1, and the numbers in a column differ by 7.
Product of left and right numbers be (x – 1)(x + 1) = x2 – 1
Product of top and bottom numbers be (x – 7)(x + 7) = x2 – 49
Difference = (Product of left and right) – (Product of top and bottom)
= (x2 – 1) – (x2 – 49)
= x2 – 1 – x2 + 49
= 48
Therefore, the difference between the product of the left and right numbers and the product of the top and bottom numbers is always 48.

Question 4.
As in the previous problem, mark a square of nine numbers in a calendar. Mark the four numbers in the corners:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Page 58 Q4
Calculate the products of the diagonal pairs of numbers and find their difference:
15 × 3 = 45
1 × 17 = 17
45 – 17 = 28
Do this for other squares of nine numbers. Explain using algebra why the difference is 28 in all cases.
Answer:
Let the middle number be x.
The number to the top left is x – 8.
The number to the top right is x – 6.
The number on the bottom left is x + 6.
The number on the bottom right is x + 8.
Product of first diagonal part = (x – 8)(x + 8) = x2 – 64
Product of second diagonal part = (x – 6)(x + 6) = x2 – 36
Difference = (x2 – 36) – (x2 – 64)
= x2 – 36 – x2 + 64
= 28
Therefore, the difference between the products of the diagonal pairs of numbers is 28.

Question 5.
A square has a perimeter of 20 centimetres. A rectangle has one side 2 centimetres longer and one side 2 centimetres shorter than a side of this square.
(i) What is the perimeter of the rectangle?
(ii) What are the areas of the square and the rectangle?
Answer:
Perimeter of the square = 20 cm
One side = \(\frac {20}{2}\) = 5 cm
(i) One side of the rectangle = 5 + 2 = 7 cm
∴ Other side = 5 – 2 = 3 cm
Perimeter of the rectangle = 2 × (7 + 3)
= 2 × 10
= 20 cm

(ii) Area of the square = side2
= 52
= 25 cm2
Area of the rectangle = 7 × 3 = 21 cm2

Question 6.
One side of a rectangle is longer than the side of a square, and the other side is equally shorter than the side of the square.
(i) What can we say about the perimeters of the square and the rectangle?
(ii) Which has the larger area, the square or the rectangle?
Answer:
Let the side of the square be x cm
One side of the rectangle = x + a
Other side = x – a (where a > 0)
(i) The perimeter of the square = 4x
Perimeter of the rectangle = 2[(x + a) + (x – a)]
= 2(2x)
= 4x
∴ The perimeter of the rectangle is equal to the perimeter of the square.

(ii) Area of the square = x2
Area of the rectangle = (x + a)(x – a) = x2 – a2
Here x2 – a2 < x2
∴ The square has the larger area.

Class 8 Maths Chapter 3 Kerala Syllabus Square Identities Questions and Answers

Class 8 Maths Square Identities Questions and Answers

Question 1.
Calculate the squares below in your head:
(i) 1012
(ii) 9.22
Answer:
(i) 1012 = 1002 + 2 × 100 × 1 + 12
= 10000 + 200 + 1
= 10201

(ii) 9.22 = (9 + 0.2)2
= 92 + 2 × 9 × 0.2 + 0.22
= 81 + 3.6 + 0.04
= 84.64

Question 2.
232 = 529
(i) What is 242?
(ii) What is 262?
Answer:
232 = 529
(i) 242 = (23 + 1)2
= 232 + 2 × 23 × 1 + 12
= 529 + 46 + 1
= 576

(ii) 262 = (23 + 3)2
= 232 + 2 × 23 × 3 + 32
= 529 + 138 + 9
= 676

Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus

Question 3.
\(\left(1 \frac{1}{2}\right)^2+\left(3 \frac{1}{2}\right)^2+\left(5 \frac{1}{2}\right)^2\) = _____________
Answer:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Extra Questions Q3

Question 4.
Find the value of \(\left(1 \frac{1}{2}\right)^2+\left(2 \frac{1}{2}\right)^2+\left(3 \frac{1}{2}\right)^2+\left(4 \frac{1}{2}\right)^2\)
Answer:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Extra Questions Q4
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Extra Questions Q4.1

Question 5.
\(\left(19 \frac{1}{2}\right)^2+\left(20 \frac{1}{2}\right)^2\) = _____________
Answer:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Extra Questions Q5

Question 6.
1012 – 1002
Answer:
1012 – 1002 = 101 + 100 = 201

Question 7.
999992 – 999982
Answer:
999992 – 999982 = 99999 + 99998 = 199,997

Question 8.
\(\left(99 \frac{1}{2}\right)^2+\left(100 \frac{1}{2}\right)^2\) = _____________
Answer:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Extra Questions Q8

Question 9.
From the following, which of the numbers will be the sum of the digits in the ones and tens place of a square of a number that ends in 5?
(a) 2
(b) 5
(c) 7
(d) 3
Answer:
(c) 7

Question 10.
If the square of a number ending in 5 is of the form 56xy. Then y – x = _____________
Answer:
y – x = 5 – 2 = 3

Question 11.
If the square of a number ending in 5 is of the form 110pq. Then p × q = _____________
Answer:
p × q = 2 × 5 = 10

Question 12.
102 + 22 = 100 + 4 = 104. By using this, write 208 as the sum of the two perfect squares.
Answer:
208 = 2 × 104
= 2(102 + 22)
= (10 + 2)2 + (10 – 2)2
= 122 + 82

Question 13.
32 + 22 = 9 + 4 = 13.
By using this, write 26 as the sum of the two perfect squares.
Answer:
26 = 2 × 13
= 2(32 + 22)
= (3 + 2)2 + (3 – 2)2
= 52 + 12

Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus

Question 14.
112 + 102 = 121 + 100 = 221.
By using this, write 442 as the sum of the two perfect squares.
Answer:
442 = 2 × 221
= 2(112 + 102)
= (11 + 10)2 + (11 – 10)2
= 212 + 12

Class 8 Maths Chapter 3 Notes Kerala Syllabus Square Identities

→ The square of the sum of two numbers is equal to the sum of the squares of these numbers and twice their product.

→ (x + y)2 = x2 + y2 + 2xy for all numbers x and y.

→ To get the square of one more than a number, we need only add the square of the number, twice the number, and one.

→ (x + 1)2 = x2 + 2x + 1 for all numbers x.

→ The square of the difference of two numbers is twice their product subtracted from the sum of their squares.

→ (x – y)2 = x2 + y2 – 2xy for all numbers x and y.

→ The product of any two numbers is the difference of the squares of half their sum and half their difference.

→ The difference of the squares of two numbers is the product of the sum and difference of the numbers.

→ x2 – y2 = (x + y)(x – y) for all numbers x and y.

→ Sum of digits of a perfect square is either 1 or 4 or 7, or 9.

→ The difference of the squares of two consecutive natural numbers is their sum.

In the first chapter, we discussed the problems related to finding the squares of a number. But in this chapter, ‘Square Identities’, we are going to discuss the algebraic formulas used to simplify expressions that involve the squares of numbers. These identities follow a particular pattern, making it easier to expand without doing lengthy multiplication each time. In this chapter, we are going to discuss squares of sums, squares of differences, and differences of squares.

Squares of Sums
We have seen a method to calculate the squares of many numbers in the section Squares.

How do we find the square of 36?
Answer:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Notes 1
362 = (30 + 6)2
= 302 + (2 × 30 × 6) + 62
= 900 + 360 + 36
= 1296
Here we wrote 36 as the sum of 30 + 6 to calculate its square.
So the square of 36 can be written as (30 + 6)2 = 302 + (2 × 30 × 6) + 62

Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus

In general, we can say that the square of the sum of two numbers is equal to the sum of the squares of these numbers and twice their product.
In algebraic form, we can write it as (x + y)2 = x2 + y2 + 2xy for all numbers x and y.
We can see it geometrically as a result of areas:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Notes 2

Worksheet – 1

Question 1.
1. 422
2. 562
3. 732
4. 842
5. 932
Answer:
1. 422 = 402 + 2 × 40 × 2 + 22
= 1600 + 160 + 4
= 1764

2. 562 = 502 + 2 × 50 × 6 + 62
= 2500 + 600 + 36
= 3136

3. 732 = 702 + 2 × 70 × 3 + 32
= 4900 + 420 + 9
= 5329

4. 842 = 802 + 2 × 80 × 4 + 42
= 6400 + 640 + 16
= 7056

5. 932 = 902 + 2 × 90 × 3 + 32
= 8100 + 540 + 9
= 8649

To get the square of one more than a number, we need only add the square of the number, twice the number, and one.
In general, (x + 1)2 = x2 + 2x + 1 for all numbers x

For example, find 312?
Answer:
312 = 302 + 2 × 30 + 12
= 900 + 60 + 1
= 961

Find 212?
Answer:
212 = 202 + 2 × 20 + 12
= 400 + 40 + 1
= 441

Find 512?
Answer:
512 = 502 + 2 × 50 + 12
= 2500 + 100 + 1
= 2601

Find 612?
Answer:
612 = 602 + 2 × 60 + 12
= 3600 + 120 + 1
= 3721

Find 712?
Answer:
712 = 702 + 2 × 70 + 12
= 4900 + 140 + 1
= 5041

Find 1012?
Answer:
1012 = 1002 + 2 × 100 + 12
= 10000 + 200 + 1
= 10201

Suppose take y as \(\frac {1}{2}\), we get
(x + \(\frac {1}{2}\))2 = x2 + x + \(\frac {1}{4}\) for all numbers x
It can also be written in the form, (x + \(\frac {1}{2}\))2 = x(x + 1) + \(\frac {1}{4}\)

For example, Find \(1 \frac{1^2}{2}\)?
Answer:
\(\mathbf{1} \frac{1}{2}^{\mathbf{2}}=1^2+1+\frac{1}{4}=2 \frac{1}{4}\) = 2.25

Find \(9 \frac{1^2}{2}\)?
Answer:
\(9 \frac{1^2}{2}=9 \times 10+\frac{1}{4}=90 \frac{1}{4}\) = 90.25

Find \(10 \frac{1^2}{2}\)?
Answer:
\(10 \frac{1}{2}^2=10 \times 11+\frac{1}{4}=110 \frac{1}{4}\) = 110.25

Find \(19 \frac{1^2}{2}\)?
Answer:
\(19 \frac{\frac{1}{2}^2}{2}=19 \times 20+\frac{1}{4}=380 \frac{1}{4}\) = 380.25

Find \(6 \frac{1^2}{2}\)?
Answer:
\(6 \frac{1}{2}^2=6^2+6+\frac{1}{4}=42 \frac{1}{4}\) = 42.25

Find \(12 \frac{1^2}{2}\)?
Answer:
\(12 \frac{1^2}{2}\) = 122 + 12 + \(\frac {1}{4}\)
= 144 + 12 + \(\frac {1}{4}\)
= 156\(\frac {1}{4}\)
= 42.25

Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus

For any non-zero number x, we get
\(\left(x+\frac{1}{x}\right)^2=x^2+\frac{1}{x^2}+2\)

For example, Find \(3 \frac{1}{3}^2\)?
Answer:
\(3 \frac{1}{3}^2=\left(3+\frac{1}{3}\right)^2=3^2+\frac{1}{3^2}+2=9+\frac{1}{9}+2=11 \frac{1}{9}\)

Find \(4 \frac{1}{4}^2\)?
Answer:
\(4 \frac{1}{4}^2=\left(4+\frac{1}{4}\right)^2=4^2+\frac{1}{4^2}+2=16+\frac{1}{16}+2=18 \frac{1}{16}\)

Find \(10 \frac{1}{10}^2\)?
Answer:
\(10 \frac{1}{10}^2=\left(10+\frac{1}{10}\right)^2=10^2+\frac{1}{10^2}+2=100+\frac{1}{100}+2=102 \cdot \frac{1}{100}\)

Worksheet – 2

Question 1.
1. \(\left(5 \frac{1}{5}\right)^2\)
2. \(\left(30 \frac{1}{30}\right)^2\)
3. \(\left(100 \frac{1}{100}\right)^2\)
4. \(\left(3 \frac{1}{2}\right)^2+\left(3 \frac{1}{3}\right)^2\)
5. \(\left(10 \frac{1}{2}\right)^2+\left(10 \frac{1}{3}\right)^2\)
Answer:
Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus Notes 3

Square of a number ending in 5:
The square of any number with the last digit (the digit in the one’s place) 5 has 25 as the last two digits.
The last digit of any number is the remainder on division by 10.
So a number ending in 5, divided by 10, leaves a remainder of 5.
The general form of such a number is 10n + 5.
The square of a number in this form is:
(10n + 5)2 = (10n)2 + (2 × 10n × 5) + 52
= 100n2 + 100n + 25
= 100(n2 + n) + 25
= 100n(n + 1) + 25
The last two digits of 100n(n + 1) are zeroes.
∴ The last two digits of 100n(n + 1) + 25 is 2 and 5

For example: Find 352?
Answer:
352 = 100 × 3 × 4 + 25 = 1225

Find 552?
Answer:
552 = 100 × 5 × 6 + 25 = 3025

Remainders on dividing natural numbers by 3:
If we consider any number, it will be a multiple of 3 or the number that leaves a remainder of 1 or 2 on division by 3.
That means, the general form of a number which is not a multiple of 3 is 3n + 1, where n = 0, 1, 2, 3,… or 3n + 2, where n = 0, 1, 2, 3,……….

The square of any non-multiple of 3 leaves a remainder of 1 on division by 3.
That means, (3n + 1)2 = 9n2 + 2 × 3n × 1 + 1
= 9n2 + 6n + 1
= 3(3n2 + 2n) + 1
= multiple of 3 + 1
Here, the remainder is 1.
(3n + 2)2 = 9n2 + 12n + 4
= 3(3n2 + 4n) + 4
= 3(3n2 + 4n) + 3 + 1
= 3(3n2 + 4n + 1) + 1
= multiple of 3 + 1
Here also the remainder is 1.
Any perfect square leaves a remainder of 0 or 1 on division by 3.
Any number that leaves a remainder of 2 on division by 3 is not a perfect square.

Worksheet – 3

Question 1.
Calculate
(i) 452
(ii) 2052
(iii) 5552
Answer:
(i) 452 = (100 × 4 × 5) + 25
= 2000 + 25
= 2025

(ii) 2052 = (100 × 20 × 21) + 25
= 42000 + 25
= 42025

(iii) 5552 = (100 × 55 × 56) + 25
= 308000 + 25
= 308025

Squares of Differences
The square of the difference of two numbers is twice their product subtracted from the sum of their squares.
If x and y are any two numbers.
Then, (x – y)2 = x2 + y2 – 2xy for all numbers x and y.

For example: Compute 582.
Answer:
582 = (60 – 2)2
= 602 – 2 × 60 × 2 + 22
= 3600 – 240 + 4
= 3364

If the equations of squares of sums and differences are added together, we get (x + y)2 + (x – y)2 = 2(x2 + y2)
Therefore, 2(x2 + y2) = (x + y)2 + (x – y)2
The differences of this two identities is, 4xy = (x + y)2 – (x – y)2
That means xy = \(\left(\frac{x+y}{2}\right)^2-\left(\frac{x-y}{2}\right)^2\)

The product of any two numbers is the difference of the squares of half their sum and half their difference.
If all the multiples of 4 starting with 8 can be written as the difference of two perfect squares.

For example: Compute 125 × 75.
Answer:
125 × 75 = \(\left(\frac{125+75}{2}\right)^2-\left(\frac{125-75}{2}\right)^2\)
= 1002 – 252
= 9375

Worksheet – 3

Compute the following.
(i) 112 × 12
(ii) 144 × 14
(iii) 172
(iv) 392
Answer:
(i) 112 × 12 = \(\left(\frac{112+12}{2}\right)^2-\left(\frac{112-12}{2}\right)^2\)
= 622 – 502
= 1344

(ii) 144 × 14 = \(\left(\frac{114+14}{2}\right)^2-\left(\frac{114-14}{2}\right)^2\)
= 792 – 652
= 2016

(iii) 172 = (20 – 3)2
= 202 – 2 × 20 × 3 + 32
= 400 – 120 + 9
= 289

(iv) 392 = (40 – 1)2
= 402 – 2 × 40 × 1 + 12
= 1600 – 80 + 1
= 1521

Class 8 Maths Chapter 3 Square Identities Questions and Answers Kerala Syllabus

Differences of Squares
The difference of the squares of two numbers is the product of the sum and difference of the numbers.
x2 – y2 = (x + y)(x – y) for all numbers x and y.
If we take y as 1, then we get the equation as x2 – 1 = (x + 1)(x – 1)

For three consecutive natural numbers, the product of the first and the last is one less than the square of the middle number.

For example: Compute 682 – 322?
Answer:
682 – 322 = (68 + 32)(68 – 32)
= 100 × 36
= 3600

Worksheet – 4

Question 1.
Calculate
(i) 422 – 172
(ii) \(\left(10 \frac{1}{2}\right)^2-\left(9 \frac{1}{2}\right)^2\)
Answer:
(i) 422 – 172 = (42 + 17)(42 – 17)
= 59 × 25
= 1475

(ii) \(\left(10 \frac{1}{2}\right)^2-\left(9 \frac{1}{2}\right)^2=\left(10 \frac{1}{2}+9 \frac{1}{2}\right)\left(10 \frac{1}{2}-9 \frac{1}{2}\right)\)
= 20 × 1
= 20

Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus

Students often refer to Kerala State Syllabus SCERT Class 8 Maths Solutions and Class 8 Maths Chapter 1 Squares Questions and Answers Notes Pdf to clear their doubts.

SCERT Class 8 Maths Chapter 1 Solutions Squares

Class 8 Kerala Syllabus Maths Solutions Chapter 1 Squares Questions and Answers

Squares Class 8 Questions and Answers Kerala Syllabus

Perfect Squares (Page No. 11)

Question 1.
Calculate the squares given below.
(i) 642
(ii) 352
(iii) 472
(iv) 532
(v) 882
Answer:
(i) 642
642 = 602 + (2 × 60 × 4) + 42
= 3600 + 480 + 16
= 4096

(ii) 352
352 = 302 + (2 × 30 × 5) + 52
= 900 + 300 + 25
= 1225

(iii) 472
472 = 402 + (2 × 40 × 7) + 72
= 1600 + 560 + 49
= 2209

Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus

(iv) 532
532 = 502 + (2 × 50 × 3) + 32
= 2500 + 300 + 9
= 2809

(v) 882
882 = 802 + (2 × 80 × 8) + 82
= 6400 + 1280 + 64
= 7744

Decimal Squares (Page No. 13)

Question 1.
Find the squares of the numbers below:
(i) 2.3
(ii) 8.7
(iii) 10.1
(iv) 12.5
(v) 15.7
Answer:
(i) 2.32 = 22 + 2 × 2 × 0.3 + (0.3)2
= 4 + 1.2 + 0.09
= 5.29

(ii) 8.72 = 82 + 2 × 8 × 0.7 + (0.7)2
= 64 + 11.2 + 0.49
= 75.69

(iii) 10.12 = 102 + 2 × 10 × 0.1 + (0.1)2
= 100 + 2 + 0.01
= 102.01

(iv) 12.52 = 122 + 2 × 12 × 0.5 + (0.5)2
= 144 + 12 + 0.25
= 156.25

(v) 15.72 = 152 + 2 × 15 × 0.7 + (0.7)2
= 225 + 21 + 0.49
= 246.49

Class 8 Maths Chapter 1 Kerala Syllabus Squares Questions and Answers

Class 8 Maths Squares Questions and Answers

Calculate the squares given below.

Question 1.
702 = _____
Answer:
702 = 70 × 70
= 7 × 10 × 7 × 10
= 7 × 7 × 10 × 10
= 49 × 100
= 4900

Question 2.
712 = _____
Answer:
712 = 702 + 2 × 70 × 1 + 12
= 4900 + 140 + 1
= 5041

Question 3.
722 = _____
Answer:
722 = 702 + 2 × 70 × 2 + 22
= 4900 + 280 + 4
= 5184

Question 4.
752 = _____
Answer:
752 = 7 × 8 | 25 = 5625

Question 5.
8.52 = _____
Answer:
8.52 = 8 × 9 + \(\frac {1}{4}\)
= 72 + 0.25
= 72.25

Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus

Question 6.
7.42 = _____
Answer:
7.42 = 72 + 2 × 7 × 0.4 + (0.4)2
= 49 + 5.6 + 0.16
= 54.76

Question 7.
7.62 = _____
Answer:
7.62 = 72 + 2 × 7 × 0.6 + (0.6)2
= 49 + 8.4 + 0.36
= 57.76

Question 8.
75.42 = _____
Answer:
75.42 = 752 + 2 × 75 × 0.4 + (0.4)2
= 5625 + 60 + 0.16
= 5685.16

Question 9.
8.252 = _____
Answer:
8.252 = 82 + \(\frac {8}{2}\) + 0.0625
= 64 + 4 + 0.0625
= 68.0625

Question 10.
10.252 = _____
Answer:
10.252 = 102 + \(\frac {10}{2}\) + 0.0625
= 100 + 5 + 0.0625
= 105.0625

Question 11.
6.252 = _____
Answer:
6.252 = 62 + \(\frac {6}{2}\) + 0.0625
= 36 + 3 + 0.0625
= 39.0625

Question 12.
100.252 = _____
Answer:
100.252 = 1002 + \(\frac {100}{2}\) + 0.0625
= 10000 + 50 + 0.0625
= 10050.0625

Class 8 Maths Chapter 1 Notes Kerala Syllabus Squares

→ The digit in the ones place of a perfect square can only be any of these numbers: 0, 1, 4, 5, 6, or 9.

→ If a number ends in 5. The digit in the ones place of its square should be 5, and the digit in its tens place should be 2.

→ The square of an even number is always even.

→ The square of an odd number is always odd.

→ The number of factors of a perfect square is odd.

→ In the first 100 natural numbers, there are 10 perfect squares, and in the first 1000 natural numbers, there are 31 perfect squares.

A perfect square is a number that is obtained by multiplying a natural number by itself. For example, when we multiply 4 by 4, we get 16. So 16 is called the perfect square. Perfect squares are easy to recognize and have many unique patterns and properties. They are always positive, and their square roots are always natural numbers. These numbers appear frequently in mathematics, especially in geometry, like calculating the area of a square, and in algebra. In this chapter, you will learn how to find the square of an integer. And also discuss how to find the square of a decimal number.

Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus

Perfect Squares
The squares of natural numbers 1, 2, 3, … are called perfect squares.

Multiplication of two-digit numbers.
11 × 11
Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus Notes 1
In another form,
Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus Notes 2
11 × 11 = 100 + (10 + 10) + 1
That means,
112 = 102 + 2 × 10 + 12 = 121
Similarly, the square of 12
12 × 12
Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus Notes 3
12 × 12 = 100 + 20 + 20 + 4
= 102 + 2 × 20 + 22
= 144
Without drawing the cells, we can write them like this,
132 = 102 + 2 × 30 + 32 = 169
142 = 102 + 2 × 40 + 42 = 196

Square of 20 = 20 × 20
= 2 × 10 × 2 × 10
= 2 × 2 × 10 × 10
= 4 × 100
= 400

Square of 212
Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus Notes 4
2122 = 2002 + 2 × 200 × 12 + 122
= 40000 + 4800 + 144
= 44944

Square of 386
3862 = 3002 + 2 × 300 × 86 + 862
= 90000 + 51600 + 7396
= 148996

Worksheet – 1

Calculate the squares given below.
(i) 24
(ii) 56
(iii) 76
(iv) 35
(v) 91
(vi) 101
(vii) 211
(viii) 912
Answer:
(i) 576
(ii) 3136
(iii) 5776
(iv) 1225
(v) 8281
(vi) 10201
(vii) 44521
(viii) 831744

Square of 30 = 30 × 30
= 3 × 10 × 3 × 10
= 9 × 100
= 900

Square of 40 = 4 × 4 × 100
= 16 × 100
= 1600

Square of 25
Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus Notes 5
25 × 25 = 202 + 2 × 20 × 5 + 52
252 = 400 + 200 + 25
252 = 625

52 × 52 = 502 + 2 × 50 × 2 + 22
522 = 2500 + 200 + 4
522 = 2704

87 × 87 = 802 + 2 × 80 × 7 + 72
872 = 6400 + 1120 + 49
872 = 7569

Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus

Simplest method to calculate the square of integers that end in 5:
For example:
352 = 302 + 2 × 30 × 5 + 52
= 900 + 300 + 25
= 1225
In this answer 1225, if we remove the last two digits 25 we get the remaining as 12.
12 | 25
The 12 is 3 × 4.
We can check this in other numbers also.
For example:
4 | 52 = 20 (4 × 5) | 25
6 | 52 = 6 × 7 | 25 = 4225
9 | 52 = 9 × 10 | 25 = 9025
1052 = 10 × 11 | 25 = 11025
2952 = 29 × 30 | 25 = 87025
10052 = 100 × 101 | 25 = 1010025

The square of the integer ending in 5 is the multiple of the number of tens (the number obtained after removing 5 from it), with the next natural number, and joining the square of 5 with this.

Decimal Squares
Square of 15 is 152 = 225
Then 1.5 × 1.5 = \(\frac{15}{10} \times \frac{15}{10}\)
= \(\frac {225}{100}\)
= 2.25

If the length of the side of a square is 2.3 metres. Find its area.
Answer:
Area = side × side
= 2.3 × 2.3
= \(\frac{23^2}{100}\)
= \(\frac {529}{100}\)
= 5.29 sq.m
This multiplication can also be considered as a rectangle math problem

3.72 = 3.7 × 3.7
= 32 + 2 × 3 × 0.7 + (0.7)2
= 9 + 4.2 + 0.49
= 13.69
Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus Notes 6
4.32 = 4.3 × 4.3
= 42 + 2 × 4 × 0.3 + (0.3)2
= 16 + 2.4 + 0.09
= 18.49

Worksheet – 2

Calculate the squares given below.
Question 1.
6.82
Answer:
6.82 = 6.8 × 6.8
= 62 + 2 × 6 × 0.8 + (0.8)2
= 36 + 9.6 + 0.64
= 46.24

Question 2.
12.32
Answer:
12.32 = 12.3 × 12.3
= 122 + 2 × 12 × 0.3 + (0.3)2
= 144 + 7.2 + 0.09
= 151.29

Question 3.
30.52
Answer:
30.52 = 30.5 × 30.5
= 302 + 2 × 30 × 0.5 + (0.5)2
= 900 + 30 + 0.25
= 930.25

Simplest method to calculate the square of a number with the decimal part 0.5:
3.52 = 3.5 × 3.5
= 32 + 2 × 3 × 0.5 + (0.5)2
= 9 + 3 + 0.25
= 12.25

7.52 = 72 + 2 × 7 × 0.5 + (0.5)2
= 72 + 7 + 0.25
= 56.25

10.52 = 102 + 10 + 0.25 = 110.25

50.52 = 502 + 50 + 0.25 = 2550.25

We can see this in another form,
3.52 = 3 × 4 + 0.25 = 12.25
7.52 = 7 × 8 + 0.25 = 56.25
10.52 = 10 × 11 + 0.25 = 110.25

If the decimal part is 0.25:
For example:
2.252 = 22 + 2 × 2 × 0.25 + (0.25)2
= 4 + 1 + 0.0625
= 5.0625

3.252 = 32 + 2 × 3 × 0.25 + (0.25)2
= 9 + 1.5 + 0.0625
= 10.5625

Class 8 Maths Chapter 1 Squares Questions and Answers Kerala Syllabus

If we consider the right side first,
Square of the integer + half of the integer + square of 0.25

Worksheet – 3

Question 1.
Find the square of 12.25.
Answer:
12.25 = Square of 12 + half of 12 + 0.0625
= 144 + 6 + 0.0625
= 150.0625

Question 2.
Square of 30.25.
Answer:
30.25 = Square of 30 + half of 30 + 0.0625
= 900 + 15 + 0.0625
= 915.0625

Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus

Students often refer to Kerala State Syllabus SCERT Class 8 Maths Solutions and Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Notes Pdf to clear their doubts.

SCERT Class 8 Maths Chapter 2 Solutions Equal Triangles

Class 8 Kerala Syllabus Maths Solutions Chapter 2 Equal Triangles Questions and Answers

Equal Triangles Class 8 Questions and Answers Kerala Syllabus

Sides and Angles (Page No. 18, 19)

Question 1.
In each pair of triangles below, find the angles of the second triangle equal to the angles of the first triangle, and write these pairs.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 18 Q1
Answer:
(i) ∠M = ∠Z, ∠N = ∠X, ∠L = ∠Y
(ii) ∠A = ∠R, ∠C = ∠Q, ∠B = ∠P

Question 2.
In the triangles shown below,
AB = QR, BC = RP, CA = PQ
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 18 Q2
Calculate angle ∠C of triangle ABC and all angles of triangle PQR.
Answer:
In triangle ABC,
∠C =180 – (40 + 60)
= 180 – 100
= 80°
In triangle PQR,
∠P = ∠C = 80°
∠Q = ∠A = 40°
∠R = ∠B = 60°

Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus

Question 3.
In the triangle below,
AB = QR, BC = PQ, CA = RP
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 18 Q3
Calculate the other two angles of each triangle.
Answer:
AB = QR ⇒ ∠C = ∠P = 50°
CA = RP ⇒ ∠B = ∠Q = 70°
BC = PQ ⇒ ∠A = ∠R = 60°

Question 4.
The diagonal of a quadrilateral splits it into two triangles as shown below:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 18 Q4
Do these triangles have the same angles? Why?
Answer:
The diagonal is common to both triangles.
Sides of upper triangles are equal to the sides of lower triangles.
Angles opposite to equal sides are equal.

Question 5.
In the quadrilateral ABCD shown below,
AB = AD, CB = CD
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 18 Q5
Calculate all the angles of the quadrilateral.
Answer:
AD = AB, CD = CB,
AC is a common Sides of triangle ABC are equal to the sides of triangle ADC
Angles opposite to equal sides are equal.
∠ACD = 50°, ∠BAC = 30°, ∠D = 100°, ∠B = 100°
Angles are ∠A = 60°, ∠B = 100°, ∠C = 100°, ∠D = 100°

Two Angles (Page No. 24)

Question 1.
In each pair of triangles below, find the sides of the triangle on the right equal to the sides of the triangle on the left:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 24 Q1
Answer:
(i) BC = PQ, AC = PR, ∠C = ∠P
(ii) MN = XZ, ∠Z = ∠M, LM = YZ

Question 2.
In the picture, the top two sides and the bottom side of a pentagon, with equal angles and equal sides, are extended to form a triangle:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 24 Q2
(i) Are the sides of the small triangle on the left equal to the sides of the small triangle on the right? Why?
(ii) Are the left and right sides of the large triangle equal? Why?
Answer:
(i) Look at the picture
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 24 Q2.1
Sides and angles of ABCDE are equal.
Since ∠A = ∠B, then ∠PAE = ∠QBC
∠PEA = ∠QCB
In triangle PAE, side AE and angles at the ends, side BC and angles at the ends in triangle QBC are equal.
So triangles are equal.

(ii) In triangle DPQ, ∠P = ∠Q.
Sides opposite to equal angles are equal.
PD = QD

Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus

Question 3.
The sides of a triangle are equal to the sides of another triangle.
(i) Is the height from each side of one triangle to the opposite vertex equal to the height from the equal side of the other triangle to its opposite vertex? Why?
(ii) Are the areas of the two triangles equal? Why?
Answer:
(i) In the figure
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 24 Q3
AB = PQ, AC = PR, BC = QR
AM is the altitude to the side BA.
∠AMB = 90°,
PN is the altitude to the side QR.
∠PNQ = 90°
In triangle AMB and triangle PNQ,
∠B = ∠Q, ∠M = ∠N
⇒ ∠A = ∠P
Side AB of triangle AMB and angles at the ends are equal to side PQ of triangle PNQ and angles at the ends.
Triangles are equal.
Sides opposite to equal angles are equal.
So AM = PN

(ii) In triangle ABC, side BC and altitude to BC are equal to side QR and altitude to QR are equal.
Areas are equal.

Two Sides (Page No. 28, 29)

Question 1.
The green lines in the picture below are parallel and of the same length; one is drawn from the end of the horizontal blue, and the other is drawn from the midpoint of the blue line:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 28 Q1
(i) Are the lengths of the red lines in the picture equal? Why?
(ii) Are the red lines parallel?
Answer:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 28 Q1.1
(i) AD = BE, AB = BC, ∠DAB = ∠EBC
In the triangles ABD and BCE, two sides and the angle between them are equal.
Sides opposite to equal angles are equal: BD = CE

(ii) Angle ABD, angle BCE are equal.
Side BD and CE are parallel.

Question 2.
Is the quadrilateral below a parallelogram? Why?
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 28 Q2
Answer:
∠BAC = ∠DCA, AB = CD
Line AB and CD are equal and parallel.
In triangle ABC and in triangle ADC line AC is common.
Two sides and the angle between them are equal.
AD = BC, ∠DAC = ∠BCA
Opposite sides of ABCD are equal and parallel.
ABCD is a parallelogram.

Question 3.
In the figure below, the lines AB and CD are parallel. M is the midpoint of AB.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 28 Q3
(i) Are the quadrilaterals AMCD and MBCD parallelograms? Why?
(ii) Calculate all the angles of the triangles AMD, MBC, and DCM.
Answer:
(i) Opposite sides are equal and parallel
AM = CD = 3, AM is parallel to CD
AMCD is a parallelogram. MBCD is also a parallelogram.

(ii) ∠MCD = 40°, ∠MDC = 60°,
∠ADM = 140 – 60 = 80°
∠AMD = 180 – (40 + 80) = 60°
∠MCB = 120 – 40 = 80°
∠AMC = 140°
∠DMC = 180 – (60 + 40) = 80°

Question 4.
In the picture, O is the centre of the circle and A, B, C, D are points on the circle:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 28 Q4
Are the lines AB and CD equal? Why?
Answer:
In triangle OAB and triangle OCD
OA = OC, OB = OD.
The angle between them is 80°.
AB = CD

Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus

Question 5.
In the picture, O is the centre of the circle and A, B, and C are points on the circle. ∠AOB and ∠AOC are equal:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 28 Q5
Are the lines AB and AC equal? Why?
Answer:
In triangle AOB and triangle AOC, OA is the common side.
OB = OC.
Including angles are equal.
Triangles are equal.
Sides opposite to equal angles are equal.
AB = AC

Isosceles Triangles (Page No. 32)

Question 1.
Find the other angles in each of the isosceles triangles below?
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 32 Q1
Answer:
(a) AB = AC
⇒ ∠B = ∠C = 30°
∠A = 180 – 60 = 120°

(b) PQ = PR
⇒ ∠Q = ∠R = \(\frac {140}{2}\) = 70°

(c) LM = MN
⇒ ∠L = 45°, ∠N = 45°

(d) XY = YZ
⇒ ∠X = ∠Z = 40°

Textbook Page No. 35, 36

Question 1.
One angle of an isosceles triangle is 120°. What are the other two angles?
Answer:
One angle is 120°.
This will be the angle between equal sides.
So the other two angles are opposite equal sides.
Each is equal to 30°.

Question 2.
The picture shows a triangle drawn by joining the centre of a circle and two points on the circle:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 35 Q2
Calculate the other two angles of the triangle.
Answer:
OA and OB are radii, equal.
So angles opposite to radii are equal to 60°.
All angles are 60°.

Question 3.
The picture shows the triangle drawn by joining three points on a circle. Two of the angles formed by joining these points to the centre of the circle are also given:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 35 Q3
(i) Calculate the third angle at the centre.
(ii) Calculate all the angles of the large (green) triangle in the circle.
Answer:
(i) In triangle OAB,
OA = OB.
The angles opposite to these sides are 35°.
∠OBA = ∠OAB = 35°
In triangle OAC,
OA = OC.
Sides opposite to these sides are equal.
Each angle is 30°.
In triangle OBC,
∠BOC = 360 – 230 = 130°
∠OBC = ∠OCB = 25°
(ii) ∠A = 65°, ∠B = 60°, ∠C = 55°

Question 4.
Calculate the areas of each of the triangles below:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Page 35 Q4
Answer:
(i) Draw AM perpendicular to BC.
Triangle AMB is a right triangle.
MB = CM = 4 cm
AM2 = 52 – 42 = 9
⇒ AM = 3
Area of triangle = \(\frac {1}{2}\) × 8 × 3 = 12 cm

(ii) Draw PN perpendicular to QR.
Triangle PNQ is a right triangle.
NQ = RN = 3 cm
PN2 = 52 – 32 = 9
⇒ PN = 4
Area of triangle = \(\frac {1}{2}\) × 6 × 4 = 12 cm

Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus

Question 5.
Given that one angle of an isosceles triangle is 70°. What can we say about the other angles?
Answer:
Two possibilities arise
(a) If two angles are 70°, then third angle will be 40°.
Angles are 70°, 70°, 40°.

(b) If one angle is 70° and the other two angles are x, then
70 + 2x = 180
⇒ 2x = 110
⇒ x = 55°
Possible triangles
70°, 70°, 40°
70°, 55°, 55°

Question 6.
How many non-equal isosceles triangles can be drawn with one angle 70° and one side 8 centimetres?
Answer:
(a) One side is 8 cm, and the angles at the ends are 40°. So the third angle will be 70°.
(b) One side is 8 cm, and the angles at the ends are 70°.
(c) Two sides are 8 cm, and the angle between them is 40°. The third angle will be 70°.
(d) Two sides are 8 cm, and the angle between them is 70°.

Class 8 Maths Chapter 2 Kerala Syllabus Equal Triangles Questions and Answers

Class 8 Maths Equal Triangles Questions and Answers

Question 1.
Four statements are given below. Identify the true statement.
(a) Equal triangles have equal area.
(b) Equiangular triangles (Triangles having equal angles) are equal triangles.
(c) Equality: one angle and any two sides of two triangles make them equal.
(d) One side and an angle at the ends can fix a triangle.
(a) (a) and (b) are true
(b) (a) and (c) are true
(c) (b) and (c) are true
(d) (a) and (d) are true
Answer:
(d) (a) and (d) are true
Equality means being identical or having the same shape and size.

Question 2.
Read the following statements and identify the correct option.
p1: A diagonal divides a parallelogram into two equal triangles.
p2: The line joining a corner to the midpoint of the opposite side of any triangle makes the triangle into two equal triangles.
(a) p1 and p2 are true
(b) p1 and p2 are false
(c) p1 is true p2 is false
(d) p1 is false p2 is true
Answer:
(c) p1 is true p2 is false

Question 3.
The base and altitude to the base of an isosceles triangle are 10 cm and 12 cm. The length of the equal sides
(a) 13 cm
(b) 15 cm
(c) 10 cm
(d) 8 cm
Answer:
(a) 13 cm
Half of the base, altitude, and one of the equal sides make a right triangle.

Question 4.
The angle around the centre of a circle is divided into three equal parts, each 120°, by drawing radii. The ends of the radii are joined to make a triangle. The triangle so formed is
(a) Right triangle
(b) Isosceles triangle
(c) Equilateral triangle
(d) None of these
Answer:
(c) Equilateral triangle
Triangles formed around the centre of the circle are equal, one angle is 120°, the Other two angles are 30°. So the angles of the triangle will be 60°.

Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus

Question 5.
Two angles of a triangle are equal, and the third is half of one of the equal angles. The small angle of the triangle is
(a) 30°
(b) 40°
(c) 36°
(d) 70°
Answer:
Divide 180° into five equal parts.
Each part is 36°.
Angles of the triangle are 72°, 72°, 36°.

Question 6.
In the diagram, AB = AD, BC = DC.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Extra Questions Q6
(a) If ∠BAC = 20°, then what is ∠A?
(b) Name pairs of equal triangles in the figure.
Answer:
(a) Triangle BAC and triangle DAC are equal.
∠BAC = ∠DAC = 20°

(b) Triangle AOB and triangle AOD are equal.
Triangle BOC and triangle DOC are equal.
Triangle ABC and triangle ADC are equal.
Triangle ABD and triangle CBD are equal.

Question 7.
In the figure, AB = AC, BD = CD.
(a) Name two equal triangles in the figure.
(b) If ∠BAC = 40°, ∠ABD = 30°, then what are the angles of triangle ADB?
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Extra Questions Q7
Answer:
(a) AB = AC, BD = CD, AD is common.
Triangle ABD and triangle ADC are equal.

(b) In triangle ADB,
∠A = 20°, ∠B = 30°, ∠D = 130°

Question 8.
In the figure, AB = CF, EF = BD, ∠and DBC = ∠AFE.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Extra Questions Q8
(a) Are the triangles AFE and triangle BDC equal? How do you know this?
(b) What are the equal sides and equal angles of these triangles?
Answer:
(a) AB = CF
∴ AB + BF = CF + BF
AF = CB,
BD = EF,
∠DBC = ∠AFE
Triangles are equal.

(b) CD = AE, EF = BD, ∠DBC = ∠AFE

Question 9.
In the figure, AB = AC, E is the midpoint of AB, and F is the midpoint of AC.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Extra Questions Q9
(a) What are the equal triangles in the figure?
(b) If BF = 12 cm, then what is CE?
Answer:
(a) AB = AC
⇒ ∠B = ∠C
BE = CF, BC is common.
Triangle BEC and triangle CFB are equal.

(b) Sides opposite to equal angles are equal.
CE = 12 cm

Question 10.
In the figure, PQ = PR = 10 cm, ∠QPS = ∠RPS.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Extra Questions Q10
(a) What are the equal triangles in the figure?
(b) If QS = 18 cm, then what is SR?
(c) Find the perimeter of PQRS.
Answer:
(a) PQ = PR
PS is common.
∠QPS = ∠RPS
Triangles PQR and triangle PRS have equal angles and sides.
(b) 18 cm
(c) 18 + 10 + 18 + 10 = 56 cm

Question 11.
In the figure, AB = AC. The lines BO and CO divide angle B and angle C equally, intersect at O.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Extra Questions Q11
(a) Prove that OB = OC.
(b) Does AO divide the angle A into two equal parts?
Answer:
(a) BO divides ∠B equally, and CO divides ∠C equally.
∠OBC = ∠OCB
⇒ BO = CO

(b) Sides of triangle OAB are equal to sides of triangle AOC.
Triangles are equal.
∠BAO = ∠CAO
OA is the bisector of A.

Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus

Question 12.
In the figure, D is the midpoint of BC, DL is perpendicular to AB, DM is perpendicular to AC, and DL = DM.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Extra Questions Q12
(a) Prove that triangle BLD and triangle CMD have the same side and shape.
(b) Is ∠B = ∠C?
(c) If AB = 12 cm, then what is AC?
Answer:
(a) BD = CD = x, DL = DM = y
Triangle BLD and triangle CMD are right triangles
BD2 = BL2 + DL2, CD2 = DM2 + CM2
Since D is the midpoint, BD = CD
BL2 + DL2 = DM2 + CM2, BL2 = CM2
⇒ BL = CM
Three sides of triangle BLD are equal to three sides of triangle CMD.
So these triangles are equal.

(b) Sides opposite to equal angles are equal,
∠B = ∠C

(c) Since ∠B = ∠C we can write AB = AC.
⇒ AB = AC = 12 cm

Class 8 Maths Chapter 2 Notes Kerala Syllabus Equal Triangles

→ If all sides of a triangle are equal to the sides of another triangle, then the triangles are equal.

→ Angles opposite to equal sides are also equal.

→ If one side and angles at the ends of that side are equal to one side and angles at the ends of another triangle, then the triangles are equal. Sides opposite to equal angles are equal. Angles opposite to equal sides are also equal.

→ A quadrilateral having opposite sides parallel and equal is called a parallelogram.

→ If two lines have equal length and are parallel, then joining ends on the same side makes a parallelogram.

→ If two sides and the angle between them in a triangle are equal to two sides and including angle of another triangle, then the triangles are equal.

→ Sides opposite to equal angles are equal.

→ Angles opposite to equal sides are equal.

Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus

→ Triangles having two sides equal are called isosceles triangles. Angles opposite to equal sides are equal.

→ Triangles having all sides equal are called equilateral triangles. All angles of an equilateral triangle are 60° each.

→ In an isosceles triangle perpendicular from the apex forming equal angles to the opposite side divides the triangle into two equal angles.

Triangles having the same shape and size are called equal triangles. The geometric conditions for becoming two triangles equal and related concepts are discussed in this unit. To fix a triangle, three measurements are essential. Three sides or one side and angles at the ends, or two sides and including angles are these measurements.

Triangles can be classified into isosceles triangles, equilateral triangles, and scalene triangles. If all sides are equal, then the triangle is called an equilateral triangle. Triangles having two sides equal are called isosceles triangles. If all sides are different, it will be a scalene triangle.

Sides and Angles
If the lengths of the sides of two triangles are the same, then their angles are also the same.
Look at these triangles:
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 1
Here, the length of the sides of the two triangles is the same, and their angles are also the same.
That is, each angle in triangle ABC is equal to one of the angles in triangle PQR. Here,

  • The longest side is 6 centimetres
  • Medium side is 5 centimetres
  • Shortest side is 3 centimetres

Thus, in each triangle,

  • The largest angle is opposite the 6-centimetre side
  • Medium angle is opposite the 5-centimetre side
  • The smallest angle is opposite the 3-centimetre side

Therefor the,

  • Largest angle is, ∠A = ∠R
  • Medium angle is, ∠B = ∠P
  • Smallest angle is, ∠C = ∠Q

If the lengths of the sides of two triangles are the same, then the angles opposite to sides of equal length are also equal.

Worksheet – 1

Question 1.
In each pair of triangles below, find all pairs of matching angles and write them down.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 2
Answer:
(i) ∠A = ∠R, ∠B = ∠P, ∠C = ∠Q
(ii) ∠L = ∠Y, ∠N = ∠X, ∠M = ∠Z

Worksheet – 2

Question 1.
Two triangles are given below.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 3
(a) Are the triangles equal? Why?
(b) If the triangles are equal, which are the matching angles?
Answer:
(a) Yes, these two triangles are equal.
Because three sides of ∆ABC are equal to three sides of ∆PQR.
ie. AB = PQ = 8 cm
BC = PR = 6 cm
AC = RQ = 4 cm
(b) ∠C = ∠R, ∠A = ∠Q, ∠B = ∠P

Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus

Two Angles
If the angles of a triangle are the same as the angles of another triangle, the lengths of their sides may not be the same.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 4
If in two triangles, the length of one side and the two angles at its ends are the same, then their third angles and the lengths of the other two sides are also the same.

If two angles of a triangle are the same as two angles of another triangle, then the third angles are also the same.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 5
In two triangles, even if all the angles and one side are the same, the other two sides may or may not be the same.
A parallelogram is a quadrilateral with each pair of opposite sides parallel.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 6
The opposite sides of any parallelogram are equal.
The opposite angles of any parallelogram are equal.

Worksheet – 3

Question 1.
In each pair of triangles below, And the pairs of sides and write their names.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 7
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 8
Answer:
(i) AB = RQ
BC = QP
AC = RP
Because the two triangles are equal, the sides opposite to the equal angles are also equal.
(ii) LN = YX, MN = ZX, LM = YZ

Two Sides
If in two triangles, the lengths of two sides and the angle between them are the same, then the length of the third side and the remaining two angles are also the same.
If two sides of a quadrilateral are equal and parallel, then the quadrilateral is a parallelogram.

Equal Triangles: If two sides and the angle between them in a triangle are equal to two sides and the included angle of another triangle, then the triangles are equal. Sides opposite to equal angles are equal. Angles opposite to equal sides are equal.

Worksheet – 4

Question 1.
In the figure below, AC and BE are parallel lines.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 9
(i) Are the lengths of BC and DE equal? Why?
(ii) Are the lengths of BC and DE equal? Why?
Answer:
AC = BE
AB = BD
Since AC is parallel to BE
∠BAC = ∠DBE [corresponding angles]
So ∆ABC and ∆BDE are equal.
(i) Since the two triangles are equal, BC = DE
(ii) Since ∠ABC = ∠BDE
BC is parallel to DE.

Question 2.
Is ACBD in the figure a parallelogram? Why?
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 10
Answer:
AC = BD = 6 cm
AB = BA
∠BAC = ∠ABD = 35°
Also, AC is parallel to BD
So ∆BAC and ∆ABD are equal.
So AD = BC and parallel.
∴ So ACBD is a parallelogram.

Worksheet – 5

Question 1.
Are the angles of ∆ABC and ∆ABD equal in the figure below? Why?
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 11
Answer:
Yes, because ∆ABC and ∆ABD are equal triangles.
AC = AD, BC = BD, also AB = AB itself.
So ∠C = ∠D, ∠CAB = ∠DAB,
∠CBA = ∠DBA (∵ In equal triangles, corresponding angles are equal)

Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus

Isosceles Triangles
A triangle with two of its sides equal is called an isosceles triangle.
See this isosceles triangle, the left and right sides are the same length.
Class 8 Maths Chapter 2 Equal Triangles Questions and Answers Kerala Syllabus Notes 12
Look at the sides of the small triangles ABM and ACM on the left and right.

  • AB = AC as mentioned above.
  • BM = CM since M is the midpoint of BC.
  • AM is a side of both these triangles.

Thus, the lengths of the sides of the triangle ABM and ACM are the same.
So, the angles opposite equal sides must also be the same.

If two sides of a triangle are equal, then their opposite angles are also equal.

A triangle with all three sides equal is called an equilateral triangle.
In any equilateral triangle, each angle is 60°.

If two angles of a triangle are equal, then their opposite sides are also equal.

In any isosceles triangle, the perpendicular from the vertex joining the equal sides to its opposite side splits this side and the angle at this vertex into equal parts.

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus

Reviewing SCERT Class 8 Basic Science Solutions and Kerala Syllabus Class 8 Basic Science Chapter 9 Cells and Cell Clusters Question Answer Notes Pdf can uncover gaps in understanding.

Class 8 Basic Science Chapter 9 Cells and Cell Clusters Question Answer Notes

Class 8 Basic Science Chapter 9 Notes Kerala Syllabus Cells and Cell Clusters Question Answer

Cells and Cell Clusters Class 8 Questions and Answers Notes

Let’s Assess

Question 1.
Identify the word pair relationship and fill the blanks.
a) compound microscope : visible light
……………….. : electron beam
b) Plant cells : eukaryote
………………… : prokaryote
c) Endoplasmic reticulum : Material transport in the cytoplasm
………………….. : Centre for production and distribution of energy
Answer:
a) Electron microscope
b) Bacteria
c) Mitochondria

Question 2.
Choose the statements related to plant cell from the following.
(a) Centrosome is present
(b) Plasma membrane is absent
(c) Plastids are present
(d) Presence of comparatively large vacuoles
Answer:
(c) Plastids are present and (d) Presence of comparatively large vacuoles

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus

Question 3.
Information related to certain cell organelles are given in the table. Complete it by selecting suitable terms from the box.
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 1
Answer:
A – f) Golgi apparatus
B – e) Chloroplast
C – d) Ribosome
D – b) Leucoplast

Basic Science Class 8 Chapter 9 Question Answer Kerala Syllabus

Answers to the indicators on page no. 136
Question 1.
Where should the slide be placed in a microscope?
Answer:
The Slide should be placed on the stage of the microscope, and the stage clip is used to keep the slide in place.

Question 2.
Which is the part that regulates the light on the slide?
Answer:
The diaphragm in the condenser controls the amount of light. The condenser lens above this focuses the light onto the object being observed. Mirror- Reflects light from the light source onto the diaphragm.

Question 3.
Which are the lenses used in microscopes?
Answer:
The eyepiece, objective lens, and condenser are the main parts of a microscope that are attached to the lens.

Question 4.
Completed illustration 9.2
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 2
Answer:
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 3

Question 5.
Completed table 9.1
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 4
Answer:

Part of a microsope Function
Eye piece lens The image formed by the objective lens is again magnified
Knobes Used to focus the lenses on the object being observed. The larger knob is called coarse adjustment and the smaller knob is called fine adjustment
Objective lens The image of the object being observed is magnified and projected into the inner surface of the eyepiece. The part where the objective lenses are mounted is called the nosepiece.
Stage Used to place slide
Clip Used to keep the slide in place
Diaphragm in condenser Control the amount of light
Condenser lens Helps focus light onto the object.
Mirror Light from the light source is reflected onto the diaphragm

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus

Question 6.
Completed table 9.2 comparing the peculiarities of different types of microscopes.
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 5
Answer:

Peculiarity Compound microcope Electron microscope
Need of light Light is needed Electron beam is used instead of light
Magnifying power Up to a thousand times It magnifies objects more than a million times more than a normal microscope
Lens Using multiple lenses Electro magnets are used

Question 7.
Note prepared based on the illustration 9.3 page 140
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 6
Answer:
A normal microscope can observe mitochondria, bacteria, red blood cells, yeast, animal cells, plant cells, paramecium, and ova. An electron microscope is an instrument that magnifies objects more than a million times larger than a normal microscope. It helps in the detailed observation of living cells, viruses, and molecular structures. An electron microscope helps in the detailed observation of DNA, viruses, and proteins, which cannot be observed under a normal microscope.

Answers to the indicators on page 141
Question 8.
While preparing the slide:
Answer:

  • Use a sharp blade for smooth, thin sections.
  • Take the thinnest sections possible. Thin sections allow light to pass through easily.
  • Cut straight across to get a proper cross-section.
  • Place the thin section on a clean glass slide.
  • Add a few drops of water or glycerin to prevent drying.
  • Cover with a cover glass using a needle to prevent air bubbles from entering.

Question 9.
Staining:
Answer:

  • Use a suitable stain such as safranin or methylene blue.
  • Stain for only a few seconds
  • Rinse gently with water to remove excess stain before covering with a coverslip.

Question 10.
Observing in high power and low power:
Answer:
Low Power: Observe with a low-power objective lens. Helps to see the epidermis, cortex, pith, etc. Adjust the mirror for a clear view.
High Power: Switch to high power to see things like xylem and phloem. Use the fine adjustment knob to adjust the clarity. Do not move the slide when switching from low power to high power.

Question 11.
Observing and illustrating:
Answer:

  • Observe carefully and patiently.
  • Draw neatly with a pencil.
  • Draw only what you see.
  • Use arrows for labelling and write names neatly.

Question 12.
Practical record on page 142 of the textbook:
Answer:
Experiment Name: Plant Stem Observation
Objective: Observe the cells in a plant stem through a microscope.
Materials Required: Microscope, plant stem, Petri dish, glass slide, cover glass, glycerin, blade, tissue paper, needle, brush, water, safranin stain, watch glass.

Procedure:
To prevent dehydration of the object to be observed, place it in Water in a Petri dish. Take thin cross-sections of the object to be observed. Transfer the sections to the water in a watch glass using a brush. Place the thinnest and most complete sections in a diluted stain taken in another watch glass. Add one or two drops of glycerin to prevent the object from drying out. Use a brush to pick up the stained section gently, then wash it in clean water and place it in glycerin on the slide. Cover it with a cover glass using a needle to prevent air bubbles from entering. Wipe off excess glycerin with tissue paper. Observe under a microscope.

Observation:
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 7
Conclusion:
Various types of cells are found in plant stems.

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus

Question 13.
Completed illustration 9.5 page 143
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 8
Answer:
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 9

Question 14.
Completed illustration 9.7 page 147
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 10
Answer:
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 11

Question 15.
Completed table 9.3 page 149
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 12
Answer:

Plant tissues Characteristics Functions
Parenchyma Contain living cells.
Thin cell wall.
Intercellular spaces are present. Cells in some parts have the ability to divide.
Perform functions such as photosynthesis and food storage.
Collenehyma A tissue made up of living cells.
The cell wall is made of substances such as cellulose and pectin.
The cell wall is thicker only in some parts.
Helps in maintaining the shape of plant parts.
Selerenehyma A tissue consists of dead cells.
Thick-cell-wall.
The cell wall is of uniform thickness throughout.
Providing strength and support to plant parts.
Xylem Made up of cells of different shapes and sizes. Conduction of water and salt to the leaves take place through xylem.
Phloem Made up of cells of different shapes and sizes. Carries food synthesised by the leaves to different parts of the plant body.

Question 16.
Completed illustration 9.9 page 151
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 13
Answer:
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 14

Question 17.
Completed illustration 9.10 page 152
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 15
Answer:
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 16

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus

Question 18.
Completed table 9.4 page 153
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 17
Answer:

Part Plant cell Animal cell Function
Cell wall present Absent Provides protection and shape to the cell
Centrioles Absent Present Helps in cell division
Plastids Present Not present Helps in the production and storage of food.
Lysosome Absent Present Destroying foreign objects

Class 8 Basic Science Chapter 9 Question Answer Extended Activities

Question 1.
Prepare models of Plant cell and Animal cell using materials available in your surroundings.

Question 2.
Prepare a picture chart showing the diversity of cells and exhibit it in the class.
Answer:
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 18

Question 3.
Prepare a timeline showing the development of cytology and present it in the class.
Answer:
Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 19

Cells and Cell Clusters Class 8 Notes

Class 8 Basic Science Cells and Cell Clusters Notes Kerala Syllabus

  • Cell biology is the study of cells.
  • Human eye can distinguish two spots having a distance of 0.2 mm in adequate light. This distance is called resolution of the eye.
  • A simple microscope in which a single lens is used, can magnify an object upto 10 times than the original size, while in a compound microscope, in which more than one lens is used, can magnify an object up to 1000 times.
  • Magnification power of a lens is its ability to magnify objects.
  • Electron microscope is an instrument that magnifies objects more than a million times. It helps to observe cells, viruses and molecular structure in detail.
  • In electron microscope electron beam is used instead of light.
  • In 1934 German scientists Ernest Raska and Max Knoll invented electron microscope.
  • The various parts of a plant cell are the cell wall, cell membrane or plasma membrane, cytoplasm, and cell organelles.
  • Organelles are parts found in the cytoplasm that perform functions necessary for the survival of the cell.
  • The organelles in plant cells are nucleus, Golgi apparatus, endoplasmic reticulum, and mitochondria, chloroplast, ribosome, vacuole, etc.
  • Plastids are specialized parts of plant cells that help produce and store food. Chloroplast, chromoplast and leucoplasts are different forms of plastids.
  • The group of similar type of cells are known as tissues. Tissues that are composed of similar type of cells are known as simple tissues. Xylem and phloem are composed of cells with different shape and size. So they are called complex tissues.
  • Meristermatic tissues are composed of cells that are capable of continuous division. Meristematic cells cause growth of plants. Cell clusters or tissues that have lost their ability to divide are known as permanent tissues, Parenchyma, sclerenchyma, collenchyma, xylem arid phloem are examples for permanent tissues.
  • Some organelles, such as lysosomes and centrioles, are found in animal cells that are not found in plant cells.
  • Tissues composed of group of similar cells perform various functions in the body of animals are called animal tissues. Epithelial tissue, Connective tissue, Muscle tissue, and Neural tissue are different types of animal tissues.
  • Stem cells are specialised cells that can develop into various types of cells such as muscle cells, nerve cells, blood cells, etc. Stem cells help to eliminate damaged cells, promote the growth of new cells and maintain healthy tissues.

INTRODUCTION

Imagine looking at your hand, or a leaf from a tree, or even a tiny ant. Have you ever wondered what these living things are made of? Well, just like a building is made of many bricks, all living organisms, from the smallest bacteria to the largest elephant, are made up of tiny basic units called cells.

Cells are often called the “building blocks of life” because they are the smallest units that can perform all the functions necessary for life, like taking in nutrients, growing, and reproducing. They are so tiny that you can’t see them with your naked eye; you need a special instrument called a microscope to observe them.

In this chapter, we’re going to explore the amazing world of cells. We’ll learn about what a cell looks like and its different parts, how different cells come together to form cell clusters (Tissues), Cell theory, and contributions of different scientists in this field.

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus

HISTORY OF CELL BIOLOGY

  • Cell biology is the study of cells.
  • Matthias Jakob Schleiden discovered that all plants are composed of cells.
  • Theodor Schwann discovered that all animals are composed of cells.
  • Rudolf Virchow introduced the concept that new cells are formed from pre-existing cells.

Cell Theory

    • All organisms are made up of one or more cells.
    • The cell is the basic unit of life.
    • New cells originate from pre-existing cells.
  • Different types of microscopes are used to observe very small or tiny cells. In simple microscopes, lenses are used to magnify objects.
  • The human eye can distinguish two spots having a distance of 0.2 mm in adequate light. This distance is called the resolution of the eye.
  • A lens is required to distinguish spots having a distance of less than 0.2 mm.
  • A simple microscope in which a single lens is used can magnify an object upto 10 times than its original size.
  • A compound microscope, in which more than one lens is used, can magnify an object up to 1000 times.
  • The magnification power of a lens is its ability to magnify objects. If eye piece lens magnifies the object to 10 x (10 times) and objective lens magnifies it into 40 x (40 times), the magnification power of the lens is 400 x.

Electron microscope

  • An instrument that magnifies objects more than a million times.
  • It helps to observe cells, viruses and molecular structure in detail.
  • In an electron microscope electron beam is used instead of light.
  • In 1934, German scientists Ernest Raska and Max Knoll invented the electron microscope.
  • In an electron microscope, electromagnetic lenses are used to focus a beam of electrons onto the specimen, allowing for much higher resolution imaging compared to light microscopes.

LET’S OBSERVE CELLS

  • Living organisms have cells of different shapes and sizes in their bodies.
  • The basic structure of all the different cells in a leaf and a stem is the same.

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 20

  • Cell Wall – The cell wall is the rigid outer layer of the cell membrane.
  • The cell membrane, or plasma membrane – Thin, flexible layer that surrounds the cell. Substances enter and leave the cell through the cell membrane.
  • The plasma membrane does not allow all substances to pass through. Therefore, the plasma membrane is known as the semi-permeable membrane.
  • Protoplasm – It consists of all the components inside the cell membrane, including the nucleus and cytoplasm.
  • Cytoplasm – A jelly-like fluid that fills the cell. It maintains all the organelles in their place and serves as the medium for chemical reactions.
  • Organelles are the parts found in the cytoplasm and perform the functions necessary for the survival of the cell.
  • The organelles of a plant cell are the cytoplasm, Golgi apparatus, endoplasmic reticulum, and mitochondria.
  • Nucleus – The centre that controls the cell. The chromatin network is the structure that appears like a network of threads within the nucleoplasm. During cell division, these chromatin networks condense into chromosomes.
  • Golgi Apparatus – Cell organelles that appear as stacked membrane layers. These organelles transport proteins and lipids to various parts of the cell and outside the cell, wrapped in membranous sacs.
  • Endoplasmic Reticulum – Organelles appear as a network of tubules within the cell, and serve as pathways for conducting materials. It helps in the synthesis and removal of materials required by the cell.
  • Mitochondria – The energy production centre of the cell.
  • Plastids – Specific parts in the plant cells that help in the synthesis and storage of food materials. They have a two-layered membrane. Different types of plastids perform different functions.

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 21

  • Vacuole – Stores water, nutrients and wastes. Usually, large vacuoles are seen in plant cells.
  • Ribosome – Found in the cytoplasm either freely or attached to the endoplasmic reticulum. They function as the centre for protein synthesis.

TISSUES
PLANT TISSUES

  • The group of similar type of cells are known as tissues.

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 22

  • Tissues that are composed of similar types of cells are known as simple tissues.
  • Xylem and phloem are composed of cells with different shapes and sizes. So they are called complex tissues.
  • The transport of water and salts to the leaves takes place through the xylem.
  • The food produced by the leaves is transported to various parts by the phloem tissue.
  • Meristematic tissues are composed of cells that are capable of continuous division. Meristematic cells are responsible for the growth of plants.

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 23

  • Cell clusters or tissues that have lost their ability to divide are known as permanent tissues. Parenchyma, sclerenchyma. Collenchyma, xylem and phloem are examples of permanent tissues.

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus

ANIMAL TISSUES

  • The animal body is also made up of different types of cells (Animal tissues).
  • Some organelles, such as lysosomes and centrioles, are found in animal cells that are not found in plant cells.

Cells and Cell Clusters Class 8 Questions and Answers Notes Basic Science Chapter 9 Kerala Syllabus 24
Stem cells are specialised cells that can develop into various types of cells, such as muscle cells, nerve cells, blood cells, etc.

  • Stem cells help to eliminate damaged cells, promote the growth of new cells and maintain healthy tissues.
  • In modern medicine, stem cells have great significance.
  • Despite these differences, there are many similarities among living organisms.
  • These common characteristics of living things lead us to the reality that the basis of life is one and the same.

Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus

Reviewing SCERT Class 8 Basic Science Solutions and Kerala Syllabus Class 8 Basic Science Chapter 5 Elements and Compounds Question Answer Notes Pdf can uncover gaps in understanding.

Class 8 Basic Science Chapter 5 Elements and Compounds Question Answer Notes

Class 8 Basic Science Chapter 5 Notes Kerala Syllabus Elements and Compounds Question Answer

Elements and Compounds Class 8 Questions and Answers Notes

Let’s Assess

Question 1.
Match the following

A
Element
B
Symbol
C
Base
Francium Rb continent
Curium Eu satellite
Rubidium Ti colour
Neptunium Cm country
Europium Fr planet
Titanium Np scientist

Answer:

A
Element
B
Symbol
C
Base
Francium Fr Country
Curium Cm Scientist
Rubidium Rb Colour
Neptunium Np Planet
Europium Eu Continent
Titanium Ti Satellite

Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus

Question 2.
Cl is the symbol of the element chlorine. How can we represent two chlorine atoms and one chlorine molecule using this symbol?
Answer:

  • Two chlorine atoms – 2 Cl
  • One chlorine molecule – Cl2

Question 3.
Find the number of atoms in each of the following and write which of them contains the most number of atoms.
5NH3, 2H2O, 5NO2, 4CO2

Element Number of Atoms
5NH3 5 N + (5 × 3) H = 5 N + 15 H = 20
2H2O (2 × 2)H + 2 O = 4H + 2 O = 6
5NO2 5 N + (5 × 2) O = 5 N + 10 O = 15
4CO2 4C + (4 × 2) O = 4C + 8 O = 12

Ammonia contains the most number of atoms.

Question 4.
Complete the table.
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 1
Answer:

Element Basis of nomenclature Symbol
Indium Indigo – colour In
Rutherfordium Rutherford – Scientist Rf
Germanium Germany – Country Ge
Silver Argentum – Latin name Ag

Question 5.
The names of some scientists are given.
(Dobereiner, Lavoisier, Newlands, Mendeleev)
Match the statements given below with the names given in brackets
i. The chemical and physical properties of the elements are functions of their atomic masses.
ii. Elements were divided into groups containing three elements (triads) with similar properties.
iii. The elements were classified into metals and non-metals.
iv. When the elements were arranged in ascending order of atomic masses, it was found that every eighth element was a repetition of the first, in terms of its properties.
Answer:
i. Mendeleev
ii. Dobereiner
iii. Lavoisier
iv. Newlands

Basic Science Class 8 Chapter 5 Question Answer Kerala Syllabus

Question 1.
What do you know about molecules? Try to write it.
Answer:
Molecules are tiny particles made of two or more atoms stuck together by invisible bonds, forming the basic building blocks of all matter.

Question 2.
Can you formulate a definition for molecules?
Answer:
Molecules are the smallest, independent and stable particles that have all the fundamental properties of a pure substance.
New molecules are formed through chemical reactions.

Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus

Question 3.
Let’s do an experiment.
a) Burn a magnesium ribbon which is scrubbed clean. Record your observations.
Answer:
Observation: Magnesium burns brightly in air. A white powder is obtained.

b) What is the white powder obtained as a result of the reaction?
Answer:
It is magnesium oxide, produced when magnesium reacts with oxygen.
This is an example of the formation of new molecules through chemical reactions between different types of molecules.
We can dissociate molecules to make new molecules.

Question 4.
Take some sugar in a dry boiling tube. Cover the mouth of the boiling tube with a piece of cotton. Heat the boiling tube strongly for a few minutes. Write your observations.
Observation – A black substance remains in the boiling tube.

a) What is the black substance left in the boiling tube?
Answer:
Carbon

b) What is the substance seen on the sides of the boiling tube?
Answer:
Water

We can observe that when sugar is heated, carbon and water are formed. Sugar molecules can be broken down through chemical reactions.

Question 5.
Let’s do another experiment.
Take some dilute hydrochloric acid in a test tube and add a small piece of magnesium to it. Introduce a burning incense stick to the mouth of the test tube. Record your observations.
Observation – A vigorous chemical reaction takes place. A gas is released. When the incense stick is introduced to the mouth of the test tube, the gas burns with a pop sound.

a) What is the gas produced as a result of the reaction?
Answer:
Hydrogen (H2)

b) How can we represent this reaction?
Answer:
Magnesium + Hydrochloric Acid → Magnesium Chloride + Hydrogen

Question 6.
Collect the hydrogen gas obtained in this experiment into another moisture-free test tube and introduce a burning incense stick to it. Record your observations.
Answer:
The gas burns with a popping sound. Water droplets are visible on the sides of the test tube.

а) What do you understand from the presence of water droplets on the sides of the test tube?
Answer:
Hydrogen in the test tube reacts with oxygen to form water.
Hydrogen + Oxygen → Water

Henry Cavendish proved that water is a substance made up of more than one element. His experiment of burning hydrogen gas in the presence of oxygen helped to know about the components of water.
In 1806, Sir Humphry Davy discovered that water could be split into hydrogen and oxygen by passing electricity through it.

Question 7.
Which are the substances obtained when water is dissociated?
Answer:
Hydrogen and Oxygen

Question 8.
Can hydrogen and oxygen be further split in to components?
Answer:
No

Question 9.
Look at the table below

Molecules Atoms in a molecule
Ammonia One atom of nitrogen
Three atoms of hydrogen
Oxygen Two atoms of oxygen
Chlorine Two atoms of chlorine
Methane One atom of carbon
Four atoms of hydrogen
Hydrogen Two atoms of hydrogen
Carbon dioxide One atom of carbon
Two atoms of oxygen

a) Which molecules in the table consist of the same type of atoms?
Answer:
Oxygen, Chlorine, Hydrogen

b) Which of these molecules consist of different types of atoms?
Answer:
Ammonia, Methane, Carbon dioxide

  • Elements are pure substances made up of the same type of atoms. They cannot be further divided into components through chemical reactions.
  • Compounds are pure substances formed by the combination of atoms of two or more elements in a fixed ratio. These can be dissociated into constituent elements through chemical reactions.

Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus

Question 10.
Categorise the following into elements and compounds.
Oxygen, water, salt, sugar, carbon, nitrogen, carbon dioxide, ammonia, magnesium oxide
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 2
Answer:

Elements Compounds
• Oxygen
• Carbon
• Nitrogen
• Water
• Salt
• Sugar
• Carbon dioxide
• Ammonia
• Magnesium oxide

Question 11.
Note the list of other elements represented by the first letter of their name. Expand the list by adding more elements.
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 3
Answer:

Element Symbol
Carbon C
Nitrogen N
Sulphur S
Oxygen O
Boron B
Phosphorus P
Fluorine F
Iodine I
Vanadium V
Yttrium Y
Uranium U

Question 12.
The element Helium is represented by the symbol ‘He’. The first and second letters of the English name are used here. What could be the reason?
Answer:
H is the symbol for hydrogen. More than one element may have the same first letter.

  • Some elements are represented by another, letter along with the first letter of the English name in upper case. See more examples of using two letters as symbols.
Element Symbol
Aluminium Al
Chlorine Cl
Curium Cm
Calcium Ca
  • The first letter of the English name is used upper ease along with the second letter or any other prominent letter in lower case.

Question 13.
Find more examples and expand the list.
Answer:

Element Symbol
Germanium Ge
Neon Ne
Manganese Mn
Cobalt Co
Zinc Zn
Beryllium Be
Magnesium Mg
Barium Ba
Radium Ra
Silicon Si

Some elements have symbols based on their Latin names.

Question 14.
Find more examples and expand the list.
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 4
Answer:

Element Latin name Symbol
Sodium Natrium Na
Potassium Kalium K
Iron Ferrum Fe
Gold Aurum Au
Copper Cuprum Cu
Silver Argentum Ag
Tin Stannum Sn
Lead Plumbum Pb
Antimony Stibium Sb
Mercury Hydrargyrum Hg
Element Latin name Symbol

• The symbol “W” is derived from the German name ‘Wolfram’ for the metal tungsten.

Question 15.
Find put how the elements given below got their names.
• Chromium
• Iridium
• Neptunium
Answer:
• Chromium – From the world “chroma,” meaning colour.
• Iridium – From the word “Iris,” meaning Rainbow.
• Neptunium – From the name of the planet “Neptune”.

Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus

Question 16.
Analyse the Periodic Table and write down the name and symbol of any 5 elements.
Answer:

  • Lithium (Li)
  • Sodium (Na)
  • Beryllium (Be)
  • Magnesium (Mg)
  • Calcium (Ca)

Question 17.
Find out which elements were added last to the periodic table.
Answer:

  • Nihonium (Nh)
  • Flerovium (Fl)
  • Livermorium (Lv)
  • Tennessine (Ts)
  • Oganesson (Og)

Question 18.
List the elements existing in solid, liquid and gaseous state with the help of periodic table.
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 5
Answer:

Solid Liquid Gas
Lithium Caesium Hydrogen
Sodium Francium Nitrogen
Potassium Mercury Oxygen
Rubidium Gallium Fluorine
Beryllium Bromine Chlorine
Magnesium Helium
Calcium Neon
Strontium Argon
Barium Krypton
Radium Xenon
Radon

Question 19.
Find the synthetic elements with the help of the periodic Table.

  • Technetium
  • Dubnium
  • Bohrium
  • Meitnerium
  • Roentgenium
  • Nihonium
  • Moscovium
  • Tennessine
  • Promethium
  • Plutonium
  • Curium
  • Californium
  • Fermium
  • Nobelium
  • Rutherfordium
  • Seaborgium
  • Hassium
  • Darmstadtium
  • Copemicium
  • Flerovium
  • Livermorium
  • Oganesson
  • Neptunium
  • Americium
  • Berkelium
  • Einsteinium
  • Mendelevium
  • Lawrencium

Question 20.
Is there any difference between 2N and N2?
Answer:
2N refers to two free nitrogen atoms. N2 refers to a nitrogen molecule formed by two nitrogen atoms bonded together.

  • 2N – refers to two free nitrogen atoms.
  • N2 – refers to a nitrogen molecule formed by two atoms.
  • 2N2 – refers to two nitrogen molecules.

Question 21.
What is the total number of atoms in 2N2?
Answer:
2N2 refers to two nitrogen molecules (N2 + N2)
2 atoms in a nitrogen molecule.
Total number of atoms in 2N2 = 2 + 2 = 4

Question 22.
Check the abbreviation of the molecules of some elements.
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 6
Answer:

Molecule Number of atoms Category
He 1 Monoatomic elements.
O2 2 Diatomic elements.
S8 8 Polyatomic elements.
H2 2 Diatomic elements
P4 4 Polyatomic elements
Ne 1 Monoatomic element
Cl2 2 Diatomic elements
Ar 1 Monoatomic element
O3 3 Triatomic element

Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus

Question 23.
Is it clear that, monoatomic elements are elements that have only one atom in a molecule? Write the difference between diatomic elements and polyatomic elements.
Answer:
Diatomic elements are elements that have two atoms in a molecule. Elements that have more than three atoms in a molecule are called polyatomic elements.

Chemical formula of the molecule represent one molecule of a substance.

Question 24.
Find the number of molecules and the total number of atoms in the following.
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 7
Answer:

Substance No. of molecules No. of atoms
H2 1 1 × 2 = 2
5O2 5 5 × 2 = 10
6N2 6 6 × 2 = 12
4Cl2 4 4 × 2 = 8
8 1 1 × 8 = 8

Question 25.
Write the symbols for hydrogen and chlorine.
Answer:
Hydrogen – H
Chlorine – Cl
A molecule of hydrogen chloride contains one hydrogen atom and one chlorine atom.
We represent a molecule of hydrogen chloride as HCl.

Question 26.
How can we represent a molecule of water in the same way?
Answer:
H2O

Question 27.
Complete the table.
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 8
Answer:
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 9
A compound has a certain ratio between the number of atoms of its constituent elements.
Example: HCl =1 : 1
H2O = 2 : 1
NH3 = 1 : 3
CO2 = 1 : 2

Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus

Question 28.
Find the number of molecules and the total number of atoms present in 3CO2.
Answer:
Number of molecules = 3
Atoms C = 3 × 1 = 3
0 = 3 × 2 = 6
Total number of atoms = 9

Question 29.
Complete the table given below.
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 10
Answer:

Compound No. of molecules No. of atoms
2HCl 2 H – 2 × 1 = 2
Cl – 2 × 1 = 2
4
4SO2 4 S – 4 × 1 = 4
0 – 4 × 2 = 8
12
3C2H5OH 3 C – 3 × 2 = 6
H – 3 × 6 = 18
0 – 3 × 1 = 3
27
2C6H12O6 2 C – 2 × 6 = 12
H – 2 × 12 = 24
O – 2 × 6 = 12 48

Question 30.
What are the reactants in this reaction?
Answer:
Carbon, Oxygen

Question 31.
What are the products?
Answer:
Carbon Dioxide

Question 32.
How do you write the reactants using chemical formula?
Answer:
C, O2

Question 33.
How about products?
Answer:
CO2
This chemical reaction can be represented as C + O2 → CO2

A chemical equation is the representation of a chemical reaction which helps to understand it at a glance. It uses symbols/chemical formulae to represent the reactants and products.

Question 34.
Calcium carbonate (CaCO3) decomposes to form calcium oxide (CaO) and carbon dioxide (CO2). How can this chemical reaction be represented?
Answer:
CaCO3 → CaO + CO2

Question 35.
Write the chemical equations of some chemical reactions that you are familiar with.
Answer:

  • 2H2 + O2 → 2H2O
  • H2 + Cl2 → 2HCl
  • 2Mg + O2 → 2MgO
  • CaO + H2O → Ca(OH)2
  • Mg + 2HCl → MgCl2 + H2

Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus

Class 8 Basic Science Chapter 5 Question Answer Extended Activities

Question 1.
Make models of the molecules using materials available in your surroundings.
• Carbon tetrachloride (CCl4)
• Ammonia (NH3)
• Water (H2O)
Answer:
Here are short instructions for making the molecule models:

General Materials:

  • Atoms: Different coloured clay/Play-Dough/thermocol balls (e.g., Black/Grey for C, Green for Cl, Blue
    for N, White for H, Red for O).
  • Bonds: Toothpicks or short stick pieces.

1. Carbon Tetrachloride (CCl4)

  • Atoms: 1 Carbon (large, black/grey), 4 Chlorine (smaller, green).
  • Instructions: Connect the central Carbon ball to four Chlorine balls using toothpicks, spreading them out to form the shape of carbon tetrachloride.

2. Ammonia (NH3)

  • Atoms: 1 Nitrogen (medium, blue), 3 Hydrogen (small, white).
  • Instructions: Connect the central Nitrogen ball to three Hydrogen balls using toothpicks. Arrange the Hydrogen atoms to form the base of a pyramid with Nitrogen at the top.

3. Water (H2O)

  • Atoms: 1 Oxygen (medium, red), 2 Hydrogen (small, white).
  • Instructions: Connect the central Oxygen ball to two Hydrogen balls using toothpicks. Angle the Hydrogen atoms to create a V-shaped molecule.

Question 2.
Prepare a slide presentation/chart on the history of development of Periodic Table and exhibit it in the classroom.
Answer:
The Periodic Table: A Journey of Discovery
(Slide 1 / Chart Title)
Slide 2 / Section 1: Early Groupings (1800s)

  • Dobereiner’s Triads (1829): Grouped elements in threes with similar properties.
  • Newlands Law of Octaves (1865): Noted repeating properties every eighth element when arranged by atomic weight.

Slide 3 / Section 2: Mendeleev’s Breakthrough (1869) ‘

  • Dmitri Mendeleev: Arranged elements by increasing atomic weight.
  • Key Insight: Left gaps for undiscovered elements and predicted their properties.
  • Significance: His predictions were later proven correct, validating his table.

Slide 4 / Section 3: Moseley’s Refinement (1913)

  • Henry Moseley: Discovered that elements are best arranged by increasing atomic number (number of protons).
  • Impact: Fixed drawbacks in Mendeleev’s table, leading to the modern version.

Slide 5 / Section 4: The Modem Periodic Table

  • Basis: Organised by increasing atomic number.
  • Structure: Elements with similar properties fall into the same groups (columns).
  • Importance: Essential tool for understanding chemistry and predicting element behaviour.

Elements and Compounds Class 8 Notes

Class 8 Basic Science Elements and Compounds Notes Kerala Syllabus

  • When sugar is heated, carbon and water are formed. Sugar molecules can be broken down through chemical reactions.
  • Molecules are the smallest particles obtained by dissociating various substances having their fundamental properties.
  • Atoms are obtained when molecules are split.
  • Dalton’s Atomic theory
    • All matter is made up of minute particles called atoms.
    • An atom is the smallest particle that can participate in a chemical reaction.
    • An atom cannot be divided during a chemical reaction.
    • An atom cannot be created or destroyed.
    • All atoms of an element are of the same size, property and mass.
    • Atoms of different elements differ in their size, property and mass.
  • Elements are pure substances made up of the same type of atoms. They cannot be further divided into components through chemical reactions.
  • Compounds are pine substances formed by the combination of atoms of two or more elements in a fixed ratio. These can be dissociated into constituent elements through chemical reactions.
  • A symbol represents an atom of an element.
  • The modern symbol system of representing elements by letters was introduced by a scientist named Berzelius.
  • The element hydrogen is represented by the letter ‘H’. That is, the first letter of name of the element is used here as the symbol.
  • Some elements are represented by another, letter along with the first letter of the English name in upper case.
  • The first letter of the English name is used upper case along with the second letter or any other prominent
    letter in lower case.
  • Some elements have symbols based on their Latin names.
  • Elements are named on the basis of country, scientists, colour, name of planets, satellites, continents, etc. Example: Francium (Country – France)
    Einsteinum (Scientist – Albert Einstein)
  • Lavoisier made the earliest attempts to classify elements. He classified the then-known elements into metals and non-metals.
  • Dobereiner classified the elements of similar properties into groups of three. These groups were called triads. He stated that the atomic mass of the element in the middle of the triads was approximately the average of the atomic masses of the other two elements. Only a few elements could be classified in this way.
  • Newlands found that when elements were arranged in ascending order of atomic mass, each eighth element was a repetition of the first in its properties. He compared this to the seven notes in music. This classification was known as the Law of Octaves.
  • A scientist named Mendeleev arranged the 63 elements known till that day in ascending order of their atomic masses and prepared a table. It was found that elements with common properties were repeated at regular intervals.
  • Mendeleev’s periodic law: The physical and chemical properties of elements are the periodic functions of their atomic mass.
  • The horizontal rows in the table are called periods and the vertical columns are called groups. Elements in a group show similar chemical properties.
  • Advantages of Mendeleev’s periodic table:
    • Elements were arranged in the ascending order of atomic mass.
    • Blank spaces were left for elements to be discovered and their properties were predicted.
    • Elements with similar properties were grouped together to simplify the study of elements and their compounds.
  • • Limitations of Mendeleev’s periodic table
    • The order of atomic mass was not strictly followed in the case of all elements. Hydrogen could not be given an exact position.
    • Elements with very different properties had to be placed in the same group.
  • Henry Moseley later discovered that the properties of elements depend on their atomic number. The periodic table developed by him is the modern periodic table used today.
  • Chemical formula of the molecule represent one molecule of a substance.
  • Atomicity is the number of atoms in a molecule.
  • In diatomic and polyatomic elements, the atomicity is written as a subscript on the right of the symbol to obtain their chemical formula.
  • The total number of molecules is written on the left side of the chemical formula.
  • A chemical equation is the representation of a chemical reaction which helps to understand it at a glance. It uses symbols/chemical formulae to represent the reactants and products.

Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus

INTRODUCTION

All the objects we see around us are made up of different molecules. Atoms are the smallest particles that are obtained by dividing molecules. Elements are pure substances that contain the same type of atoms. 118 Elements have been discovered so far. Compounds are formed when atoms of elements combine with each other. In the language of chemistry, symbols are used to represent elements, and chemical formulas are used to represent compounds. The periodic table, which has been prepared by classifying the elements comprehensively, makes the study of compounds and elements easier. In this unit, we will learn about the origins of element names, their symbols, chemical formulas of molecules, and the history of element classification.

We know that all objects around us are made up of different molecules. Let us examine how each of these molecules differ with respect to their structural characteristics.

ATOM

  • Molecules are the smallest particles obtained by dissociating various substances having their fundamental, properties.
  • Atoms are obtained when molecules are split.
  • The molecules of every substance are made up of minute atoms. All substances in the universe are made up of atoms. The word “atom” comes from the Greek word “atomos,” which means indivisible.
  • Democritus proposed that all matter is made up of indivisible particles called atoms.
    In 1807, John Dalton proposed the atomic theory to explain the nature of atom. Dalton’s Atomic Theory is one of the important theories in modem chemistry. The ideas put forward by Dalton are given below.

    • All matter is made up of minute particles called atoms.
    • An atom is the smallest particle that can participate in a chemical reaction. .
    • An atom cannot be divided during a chemical reaction.
    • An atom cannot be created or destroyed.
    • All atoms of an element are of the same size, property and mass.
    • Atoms of different elements differ in their size, property and mass.

A water molecule is made up of two atoms of hydrogen and one atom of oxygen.

SYMBOLS

  • Symbols are used to represent concepts in a clear and simple manner. Symbols make communication and interpretation easier.
  • Similarly, signs are used to represent elements. These are known as chemical symbols. A symbol represents an atom of an element.
  • The modern symbol system of representing elements by letters was introduced by a scientist named Berzelius.
A symbol represents an atom of an element.

ORIGIN OF SYMBOLS
• The element hydrogen is represented by the letter ‘H’. That is, the first letter of name of the element is used here as the symbol.

HOW ELEMENTS GOT THEIR NAMES
Elements are named on the basis of country, scientists, colour, name of planets, satellites, continents, etc.
Example: Francium (Country – France)
Einsteinum (Scientist – Albert Einstein)

CLASSIFICATION OF ELEMENTS
In a library we can see that books are arranged by categorising them into essays, poems, stories, novels, etc, Elements are also classified in this manner. So far, 118 elements have been discovered which include natural and synthetic elements. It is very difficult to study all these elements and their compounds separately. It would be easier if elements with similar properties are classified into groups.

• The Periodic Table is a table in which all the elements are categorised and arranged based on their properties.

EARLIER ATTEMPTS FOR THE CLASSIFICATION OF ELEMENTS
The modern Periodic Table that we use today is the result of the efforts of many scientists.

  • Lavoisier made the earliest attempts to classify elements. He classified the then-known elements into metals and non-metals.
  • Dobereiner classified the elements of similar properties into groups of three. These groups were called triads. He stated that the atomic mass of the element in the middle of the triads was approximately the average of the atomic masses of the other two elements. Only a few elements could be classified in this way.
Element Atomic mass
Li 7
Na 23
K 39
Ca 40
Sr 87.6
Ba 137.3
Cl 35.5
Br 80
I 127
  • Newlands found that when elements were arranged in ascending order of atomie mass, each eighth element was a repetition of the first in its properties. He compared this to the seven notes in music. This classification was known as the Law of Octaves. As more elements were discovered, it became clear that all elements could not be arranged in this way.
Li Be B C N O F
Na Mg Al Si P S Cl
  • A scientist named Mendeleev arranged the 63 elements known till that day in ascending order of their atomic masses and prepared a table. It was found that elements with common properties were repeated at regular intervals.
The physical and chemifcal properties of elements are the periodic functions of their atomic mass.

MENDELEEV’S PERIODIC LAW
Mendeleev’s Periodic Table is shown in the figure. The horizontal rows in the table are called periods and the vertical columns are called groups. Elements in a group show similar chemical properties.
Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus 11

Elements and Compounds Class 8 Questions and Answers Notes Basic Science Chapter 5 Kerala Syllabus

CHARACTERISTICS

  • Elements were arranged in the ascending order of atomic mass. Blank spaces were left for elements to be discovered and their properties were predicted.
  • Elements with similar properties were grouped together to simplify the study of elements and their compounds.
  • However, the order of atomic mass was not strictly followed in the case of all elements. Hydrogen could not be given an exact position.
  • Elements with very different properties had to be placed in the same group.

When Mendeleev’s Periodic Table was formed in 1869, there was limited knowledge about the structure of the atom and its elementary particles. Henry Moseley later discovered that the properties of elements depend on their atomic number. The periodic table developed by him is the modern periodic table used today.

CHEMICAL FORMULA
CHEMICAL FORMULA OF MOLECULES
We use symbols to identify elements easily. If we write N, it refers to nitrogen and one atom of nitrogen.

CHEMICAL FORMULA OF ELEMENTS

  • In monoatomic elements, the symbol itself is considered as the chemical formula.
  • In monoatomic molecules, the number written on the left of the symbol indicates, the number of molecules. This is also the number of atoms.

Example: 2He → 2 Helium atoms / 2 Helium molecules
3Ne → 3 Neon atoms / 3 Neon molecules
Atomicity is the number of atoms in a molecule. In diatomic Mid polyatomic elements, the atomicity is written as a subscript on the right of the symbol to obtain their chemical formula. The total number of molecules is written on the left side of the chemical formula.
We can find the number of molecules and the number of atoms from the chemical formula of the elements.
3O2 → 3 oxygen molecules .
Total number of atoms = 3 × 2 = 6 oxygen atoms
5Cl2 → 5 chlorine molecules
Total number of atoms = 5 × 2 = 10 chlorine atoms

CHEMICAL FORMULA OF COMPOUNDS
Hydrogen and Chlorine are the constituent elements in hydrogen chloride.

CHEMICAL EQUATIONS
Carbon reacts with oxygen to form carbon dioxide.

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

Reviewing SCERT Class 8 Basic Science Solutions and Kerala Syllabus Class 8 Basic Science Chapter 6 Metals and Non Metals Question Answer Notes Pdf can uncover gaps in understanding.

Class 8 Basic Science Chapter 6 Metals and Non Metals Question Answer Notes

Class 8 Basic Science Chapter 1 Notes Kerala Syllabus Metals and Non Metals Question Answer

Metals and Non Metals Class 8 Questions and Answers Notes

Let’s Assess

Question 1.
Match the following.
Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus 1
Answer:

A B C
Name of the metal Characteristic property Symbol
Silver High electrical conductivity Ag
Platinum High ductility Pt
Gold The highest malleability Au

Question 2.
The names of certain metals are given in the box.
Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus 2
Choose the appropriate metal for the following situations.
a. Reacts with the components of air and forms tarnish on the surface.
b. It is the best conductor of heat.
c. The metal that melts when placed on the palm.
d. It exists in the liquid state in normal temperature.
e. This metal is present in bones and teeth.
Answer:
a. Copper
b. Silver
c. Gallium
d. Mercury
e. Calcium

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

Question 3.
Certain metals are given in the following table. Find any two uses of each and the characteristic property responsible for it.
Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus 3
Answer:

Metal Use Characteristic property
Copper Manufacture of electric wire Electrical conductivity, Ductility
Manufacture of utensils, Idols Malleability
Gold Manufacture of ornaments Malleability, Ductility
Manufacture of coins Metallic lustre, Malleability
Aluminium Manufacture of utensils for cooking Thermal conductivity, Malleability
Manufacture of electrical wires Electrical conductivity, Ductility
Iron Manufacture of wires, tools etc. Hardness
Used for the manufacture of sheets. Malleability
Silver Used for the manufacture of ornaments Malleability, Ductility, Metallic lustre
Used for the manufacture of coins, idols, etc. Metallic lustre, Malleability

Question 4.
Oxides of elements A and B are dissolved in water in two separate beakers.
a) How can you identify the acidic solution and the basic solution?
b) Which of these elements is more likely to be a metal? Why?
Answer:
a) Dip red and blue litmus papers in both solutions.

  • The solution which turns blue litmus red is the acidic solution.
  • The solution which turns red litmus blue is the basic solution.

b) The solution that turns red litmus into blue is formed by a metal oxide, because metal oxides are basic in nature.
Therefore, the element whose oxide formed the basic solution is more likely to be a metal.

Basic Science Class 8 Chapter 6 Question Answer Kerala Syllabus

Question 1.
You must be familiar with different kitchen utensils. What are the common materials used to make utensils for cooking?
Answer:
Aluminium, Copper, Steel, Iron

Question 2.
Let’s do an activity.
Take some water into a flat bowl. Place a wooden ladle and a steel ladle in it and let it boil. Touch the ladles and find out which one is hotter. Why is it so?
Answer:
A steel ladle heats up more because steel conducts heat.

Question 3.
Why are you warned against handling iron-like objects during thunder and lightning?
Answer:
Metals like iron are good conductors of electricity. Therefore, they are susceptible to lightning strikes.

Question 4.
Find out the characteristics of metals as indicated in the above situations.
Answer:
Thermal conductivity
Electrical conductivity

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

Question 5.
Complete the table below.
Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus 4
Answer:
Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus 5

Question 6.
What are the other characteristics of metals familiar to you?
Answer:

  • Very Hard
  • High melting point
  • High Boiling point
  • High Density

Question 7.
Define metals?
Answer:
Metals are substances that exhibit high thermal and electrical conductivity and possess lustre and hardness.

MALLEABILITY
Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus 6
Have a look at the picture.

Question 8.
What is the blacksmith doing?
Answer:
A hammer strikes the piece of metal.

Question 9.
What changes occur when a piece of metal is hammer blown?
Answer:
The piece of metal flattens into a sheet.

Question 10.
Haven’t you seen aluminium foil which is used to wrap tablets and food materials? Which characteristic property of metals is used in this case?

Malleability

Generally, metals can be hammered and flattened into thin sheets. This characteristic property of metals is known as malleability.
  • All metals are not malleable to the same extent.
  • Gold is the most malleable metal.

Question 11.
Write examples for utilising the malleability of metals.
Answer:

  • Metal sheets are used to make roofing of buildings.
  • Used for making thin foils. Aluminium foil for packaging food.
  • Used for jewellery making.
  • Metal sheets are used to make cupboards and furniture.

DUCTILITY
Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus 7

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

Question 12.
What metal is the filament of the bulb in the picture made of?
Answer:
Tungsten

Question 13.
Can you explain why tungsten is used to make the filament?
Answer:
Tungsten can be drawn into very thin wires.

Question 14.
Define Ductility
Answer:
Metals can be drawn into thin wires. This property of metals is known as ductility.

Metals like gold and copper can be drawn into very fine wires. Gold and Platinum are the most ductile metals.

Question 15.
There are a lot of situations where ductility of metals is utilized. List a few of them.
Answer:

  • Electric wires
  • Filaments in light bulbs
  • Musical instrument strings
  • Jewellery
  • Construction wires

Question 16.
Which among these objects made the bulb glow?
Answer:
A piece of razor blade, A fine iron wire, aluminium wire, Copper wire,

Question 17.
Are they metals or non-metals?
Answer:
They are metals
The ability of a material to conduct electricity through it is known as electrical conductivity. All metals are electrical conductors.
Silver is the best electrical conductor among the metals. The electrical conductivity of the metals such as silver, copper, gold, and aluminium decreases in the following order.
Silver > Copper > Gold > Aluminium

Question 18.
Which metal is used in household electrical wiring?
Answer:
Copper

Question 19.
Which metal is used to make electric lines for the public distribution of electricity?
Answer:
Aluminium

Question 20.
Why is silver not used for this purpose?
Answer:
High Cost
Low availability

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

Question 21.
Utensils for cooking are usually made of metal. Which characteristic properties of metals are utilised in this case?
Answer:
Thermal conductivity
Malleability

Question 22.
Define thermal conductivity.
Answer:
The ability of metals to conduct heat is called thermal conductivity. It is one of the fundamental characteristics of metals.

Silver is the best conductor of heat among metals. Metals such as aluminium and copper have relatively high thermal conductivity.

Question 23.
Aluminium is extensively used for cooking utensils. Find the reasons.
Answer:

  • High Thermal Conductivity
  • Malleability
  • More availability
  • Low cost

The non-metal carbon exists in two main allotro ic forms, diamond and graphite

Diamond Graphite
High thermal conductivity High electrical conductivity
It is used to cut glass It is used as electrode

The strikingly different properties of diamond and graphite are due to the differences in the carbon
carbon bonding in them.

Question 24.
Give examples of situations where sonority is useful.
Answer:

  • Bells, church bells
  • Gongs of bells
  • Musical Instruments

Question 25.
Identify the situations in which metallic lustre is made use of?
Answer:

  • For making ornaments.
  • Mirrors and Reflectors.
  • Utensils and Cookware.

Question 26.
Is it possible to cut metals such as copper, aluminium and gold in the same manner?
Answer:
No. Lithium, sodium and potassium are soft metals. But other metals are harder.

Question 27.
Give an example of a hard metal.
Answer:
Iron, Copper, Aluminium, Gold

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

Question 28.
Give an example of soft metals.
Answer:
Lithium, Sodium, Potassium

Question 29.
Are there metals that exist in a liquid state?
Answer:
Yes

Question 30.
Write the names of metals that exist in a liquid state.
Answer:
Mercury (Hg)
Gallium (Ga)
Caesium (Cs)

  • Metals generally have high melting points
    However, gallium and caesium are metals that have low melting points. They start melting when placed on our palm. In other words, they exist in the liquid state on warmer days.
  • Metals generally have high boiling points.
  • Metals generally have high density.

Question 31.
Take some articles made up of different metals (iron nail, aluminium wire), a small piece of wood, charcoal, thermocol and cork. Put each of them one by one in water in a beaker. Which among these articles sink into the water? Which of these floats over water?
Answer:
Articles sink into the water: An Iron nail, an Aluminium wire, A small piece of wood
Articles float on water: Charcoal. Thermocol, Cork.

Metals are substances that generally exist in the solid state, exhibit high conductivity of heat and electricity, and possess Metallic lustre and hardness.

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus 8

Question 32.
What are the characteristics of non-metals in comparison with metals?
Answer:
Generally, non-metals are less hard than metals

  • They do not show sonority.
  • They generally do not conduct electricity.
  • They generally show a very low boiling point and Melting point.

Question 33.
List some non metals in your Science Diary. Classify them into solid, liquid and gas.
Answer:

Solid Liquid Gas
Boron Bromine Hydrogen
Carbon Nitrogen
Silicon Oxygen
Germanium Fluorine
Phosphorous Chlorine
Arsenic Iodine
Sulphur Helium
Neon
Argon
Krypton
Radon
Xenon

Question 34.
Observe the newly formed surface of sodium when it is cut with a knife. Record your observation.
Answer:
Good metallic lustre.

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

Question 35.
Observe the surface after keeping it exposed to air for some time. What change do you observe?
Answer:
Metallic lustre disappears, and the surface becomes dull or tarnished.

Question 36.
Why did it lose its metallic lustre?
Answer:
It is because sodium reacts with the components of air

Question 37.
Haven’t you noticed the dull appearance of the surface of old objects made of aluminium?
Answer:
Most metals react with the atmosphere to form various compounds, and this is the reason for their dull appearance.

Question 38.
Take an aluminium wire and scrub it with sandpaper. What change do you observe?
Answer:
When you scrub an aluminium wire with sandpaper, you observe that the dull surface becomes shiny or lustrous again.
Most metals, such as copper and magnesium, react with air in a similar manner.

Question 39.
Burn a piece of magnesium in air. What is left behind?
Answer:
Magnesium reacts with oxygen in the air to form the compound magnesium oxide.
Magnesium + Oxygen → Magnesium oxide
2Mg + O2 → 2MgO

Question 40.
a) Dissolve the magnesium oxide formed, in water taken in a beaker. What is the colour change when a red litmus paper is dipped in it?
b) What is the reason?
Answer:
a) Red litmus paper changes to blue.
b) Magnesium oxide dissolves in water to form magnesium hydroxide, which is a base.

  • Most of the metals (except silver, gold and platinum) react with oxygen in air to form the corresponding oxide.
  • Almost all the metal oxides show a basic nature in the presence of water.
  • Some metals react with the components of air like moisture and carbon dioxide in addition to oxygen.
    Oxides of metals are generally basic in nature.

OXIDES OF NON-METALS
Carbon combines with oxygen to form carbon dioxide.
C + O2 → CO2

Question 41.
Do you know how soda water is prepared?
Answer:
Soda water is prepared by dissolving carbon dioxide in water at high pressure.
CO2 + H2O → H2CO3

Question 42.
Dip a blue litmus paper in soda water. Notice the change in colour.
Answer:
When a blue litmus paper is dipped in soda water, the blue litmus paper will turn red.
It is clear that soda water is acidic in nature. Carbonic acid is present in soda water.

Oxides of nonmetals are generally acidic in nature.

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

Question 43.
What is Metal Corrosion?
Answer:
Metals react with different components of air and form various compounds. This is known as metal corrosion.
Examples:
Rusting of iron
Copper tarnishes.
Metals lose their lustre.

Question 44.
What are the factors that influence the rusting of iron?
Answer:

  • Presence of oxygen and moisture.
  • Presence of impurities.
  • Temperature.
  • Presence of salts like common salt accelerates the rusting process of iron.

EXPERIMENT
Materials required

Clean and dry test tubes (4), cork (4), rust-free and shiny iron nails (4), anhydrous calcium chloride, table salt, ordinary water, distilled water, boiled distilled water, and oil.

Procedure
Take four test tubes. Put a rust-free and shiny iron nail in each of them. Add distilled water in the first test tube, salt solution in the second test tube and distilled water soon after boiling in the third test tube. Iron nails should be fully immersed in these three test tubes. Add oil in the third test tube in such a way that the surface of the water is completely covered by oil. Take anhydrous calcium chloride or quicklime in the fourth test tube. All the four test tubes should be closed immediately with cork after putting the materials.
Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus 9

Question 45.
Keep the test tubes at rest for a few days and watch the iron nails afterwards. Indicate the test tubes in which the iron nails got rusted.
Answer:
The iron nails in the first and second test tubes have rusted.
Air and moisture are present in the first test tube.
The salt solution in the second test tube influences the rusting of iron.

Question 46.
The iron nails in the third and fourth test tubes haven’t undergone any change. What is the reason?
Answer:
Since the third test tube contains distilled water soon after boiling and oil floating on the surface of water, the iron nail cannot come in contact with air. Anhydrous calcium chloride or quicklime absorbs the moisture present in the fourth test tube.

Anhydrous calcium chloride absorbs moisture from atmosphere very quickly. Silica gel and quick lime are also used for this purpose.

Question 47.
Why was boiled distilled water used in this experiment?
Answer:
To completely remove air and achieve a high temperature.

Question 48.
Do you know why iron window bars in houses close to the seashore corrode faster?
Answer:
The presence of salt in the atmospheric air causes faster rusting of iron.

Question 49.
Besides iron, which other metals are used in our daily life that undergo corrosion in the presence of atmospheric air?
Answer:

  • Copper
  • Aluminium
  • Silver
  • Zinc

Question 50.
Very reactive metals like sodium and potassium are stored in kerosene. Can you find the reason for it?
Answer:
Highly reactive metals quickly undergo chemical reactions in the presence of air and moisture. They are stored in kerosene to avoid contact with air and moisture.

Question 51.
After cutting a lemon, if the iron knife is left without wiping, it starts rusting faster. You are familiar with the acid present in lemon, aren’t you?
Answer:
Iron rusts faster in the presence of acids. Citric acid is present in lemon.

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

Question 52.
Why are food items with having sour taste, such as pickles and curd, are not stored in vessels made of aluminium and Iron?
Answer:
Sour substances contain acids (pickles – acetic acid, curd – lactic acid). Metal vessels react with these. Therefore, pickles and curd are not stored in metal vessels.

Question 53.
Do all metals similarly undergo corrosion?
Answer:
Metals that react with components in the atmospheric air are susceptible to corrosion. Less reactive metals, such as gold, Platinum, and Silver, do not corrode quickly.

Question 54.
What are the disadvantages of the corrosion of metals

  • Causes metals to lose their shine and original appearance, becoming dull or discoloured.
  • Environmental Pollution
  • Results in economic loss
  • Leads to structural failures (bridges, buildings), leaks, and explosions in pipelines
  • Mechanical failures in vehicles and aircraft.

Question 55.
What are the methods to prevent corrosion?
Answer:

  • Painting
  • Greasing/Oiling
  • Galvanisation
  • Apply Non-Metallic coating
  • Convert to alloys

Question 56.
What are alloys?
Answer:
Metals are combined-with other metals or non-metals to make alloys.
It is done to obtain materials with desirable properties and to resist corrosion.
A very small number of non-metals like carbon, phosphorous, etc. are also added to such alloys.
For e.g:-stainless steel, brass, bronze

Question 57.
What are the advantages of alloying metal?
Answer:

  • Increased strength and Hardness
  • Preventing corrosion
  • Improve appearance
  • Improved Durability

Question 58.
The presence of certain metals is essential for the normal functioning of the human body. Give examples.
Answer:
Sodium, Potassium, Calcium, Iron, Cobalt and Zinc are examples of such metals.

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

Question 59.
Name the metal contained in haemoglobin in the blood is?
Answer:
Iron

Question 60.
Name the most abundant metal in the human body?
Answer:
Calcium

  • It gives strength to bones and teeth.
  • It helps to regulate blood pressure.

As the human body cannot synthesise those metals, they should be made available through food in sufficient quantities.

Class 8 Basic Science Chapter 6 Question Answer Extended Activities

Question 1.
Alloys have a variety of uses. Duralumin, which is used to make the parts of aircrafts and Alnico, which is used to make magnets are examples. Collect information about the alloys and their uses. Present it in your class as slides or charts.
Answer:
Hints

Alloys Components Uses
Steel Fe, C Used for the manufacture of tools, Building materials, bridges, and railway tracks
Stainless Steel Fe, Ni, Cr, C To manufacture household appliances and surgical instruments
Brass Cu. Zn To make locks, handles, and musical instruments
Bronze Cu, Sn To make medals, statues, musical instruments, etc.
Alnico Al, Ni, CO, Fe To make permanent magnets
Duralumin Al, Cu, Mg, Mn To make aircraft parts
Magnalium Mg, Al To make aircraft parts
Nichrome Ni, Cr, Fe, C To make heating coils
Solder Sn, Pb To connect electric wires
Ornamental Gold Au, Zn/Ag To make jewellery and coins

Question 2.
Metals are present not only in the human body, but in plants as well. Collect information regarding the important metals present in plants and their functions. Prepare a science article based on this.
Answer:
Metals in the plant body

  • Magnesium – The main component of chlorophyll Helps in photosynthesis
  • Potassium, Calcium – Helps with growth and nutrition
  • Cobalt, Iron, Manganese, Copper, Molybdenum, Nickel, Zinc – Plays an important role in growth, enzyme production, and metabolic functions

Metals and Non Metals Class 8 Notes

Class 8 Basic Science Metals and Non Metals Notes Kerala Syllabus

  • Metals are substances that generally exist in the solid state. Show high conductivity of heat and electricity, metallic lustre and hardness.
  • Generally, metals can be hammered and flattened into thin sheets. This characteristic property of metals is known as malleability.
  • Gold is the most malleable metal.
  • Metals can be drawn into thin wires. This property of metals is known as Ductility.
  • Metals like gold and copper can be drawn into very fine wires. Gold and Platinum are the most ductile metals.
  • The ability of a material to conduct electricity through it is known as electrical conductivity. All metals are electrical conductors.
  • Silver is the best electrical conductor among the metals.
  • The ability of metals to conduct heat, viz., thermal conductivity, is one of the fundamental characteristics of metals.
  • Silver is the best conductor of heat among metals.
  • The ability of metals to produce characteristic sound when striked with a hard material is known as sonority.
  • The shiny appearance of the surface of metals is known as metallic lustre.
  • Generally, metals are hard.
  • Metals generally have high melting point.
  • Metals generally have high boiling points.
  • Metals generally have high density.
  • Characteristics of Non-Metals
    • Generally, non-metals are less hard.
    • They do not show sonority.
    • They generally do not conduct heat.
  • Reactions of metals with atmospheric air
    • Most of the metals (except silver, gold and platinum) react with oxygen in air to form the corresponding oxide. Almost all the metal oxides show basic nature in the presence of water. Some metals react with the components of air like moisture and carbon dioxide in addition to oxygen.
  • Oxides of metals are generally basic in nature.
  • Oxides of non-metals are generally acidic in nature.
  • Metals react with different components of air and form various compounds. This is known as corrosion of metals.
  • Metals are combined with other metals or non-metals to make alloys. It is done to obtain materials with
    desirable properties and to resist corrosion. A very small amount of non-metals like carbon, phosphorus, etc. are also added to such alloys.
  • Essential metals like sodium, potassium, calcium, iron, cobalt, and zinc are crucial for normal human body functioning, with calcium being the most abundant and vital for bones, teeth, and blood pressure regulation. Since the body cannot synthesise these, they must be obtained in sufficient quantities through diet.

INTRODUCTION

It can be observed that most of the elements discovered so far are metals. The discovery and use of metals greatly accelerated the pace of human progress. Tools, machinery, construction materials, vehicles, bridges, railway tracks, ornaments, and household appliances are just a few of the numerous objects made from metals. Certain characteristics of metals make them beneficial for various uses. This unit will delve into the specific characteristics of metals that make them so versatile and invaluable, covering topics like malleability, ductility, electrical and thermal conductivity, sonority, metallic lustre, and hardness. Metals undergo corrosion due to interaction with the atmosphere. In this unit, we will understand the causes of metal corrosion and methods to prevent it, as well as the properties of non-metals.

Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus

ELECTRICAL CONDUCTIVITY
Complete the circuit as shown in the figure
Metals and Non Metals Class 8 Questions and Answers Notes Basic Science Chapter 6 Kerala Syllabus 10
A few materials are given on the table. Put them one by one in the place marked as P, Q. Repeat the experiment using more objects. Record the observation and inference.

Object Bulb glows/does not glow Conductor of electricity /not a conductor of electricity
A folded piece of paper Bulb does not glow Not a conductor of electricity
A piece of plastic scale /ruler Bulb does not glow Not a conductor of electricity
A piece of a razor blade Bulb glows Conductor of electricity
A fine iron wire Bulb glows Conductor of electricity
Aluminum wire Bulb glows Conductor of electricity
Jute Bulb does not glow Not a conductor of electricity
Piece of cloth Bulb does not glow Not a conductor of electricity
Copper wire Bulb glows Conductor of electricity
Rubber band Bulb does not glow Not a Conductor of electricity

SONORITY
The ability of metals to produce a characteristic sound when strike with a hard material is known as sonority.

METALLIC LUSTRE
The shiny appearance of the surface of metals is known as metallic lustre.
Certain metals show metallic lustre when they are cut into pieces or polished.

HARDNESS
You know that it is easy to cut sodium metal with a knife.

PROPERTIES OF METAL
• Generally, metals are hard
Metals generally exist in the solid state.

Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus

Reviewing SCERT Class 8 Basic Science Solutions and Kerala Syllabus Class 8 Basic Science Chapter 7 Let’s Cultivate and Reap Goodness Question Answer Notes Pdf can uncover gaps in understanding.

Class 8 Basic Science Chapter 7 Let’s Cultivate and Reap Goodness Question Answer Notes

Class 8 Basic Science Chapter 7 Notes Kerala Syllabus Let’s Cultivate and Reap Goodness Question Answer

Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes

Let’s Assess

Question 1.
Arrange the information given in boxes A and B in the table suitably.
Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 1
Answer:

Space constraints Synthetic fertiliser Organic fertiliser
Vertical farming. Urea Manure
Terrace farming Ammonium phosphate Vermicompost
Sack farming Superphosphate Bone meal

Question 2.
Satheesh has 15 cents of homestead land and 30 cents of paddy field. He says that paddy cultivation is not profitable. What suggestions do you have to make farming profitable by making use of the homestead land and the paddy field?
Answer:
Integrated farming methods can be adopted. There is potential for vegetable cultivation, papaya cultivation, poultry farming, and cattle farming on the land. There is potential for duck farming and rearing of fishes along with paddy cultivation in the field.

Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus

Question 3.
Which is the odd one? What are the common features of the others?
a) Wick irrigation, Vertical farming, Drip irrigation, Mulching
b) Hydroponics, aquaponics, aeroponics, geographical indication
Answer:
a) Vertical farming, others are various irrigation methods.
b) Geographical indication, others are parts of smart farming.

Question 4.
‘Farming will be profitable only if all the pests are killed!’ What is your response to this comment from a farmer? How can effective pest control be implemented?
Answer:
I do not agree with this opinion of the farmer. Pest control methods should be selected taking into account the density and nature of the crops. The farmers’ need is not to kill the entire pests, but to control their growth in a way that does not damage the crops. Integrated pest control is a method that minimises the use of pesticides through automated pest control methods using various types of /lets and traps, friendly insects, and the cultivation of seeds that are resistant to pests.

Question 5.
Observe the illustration.
Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 2
a) What are the benefits to farmers by producing such products?
b) Prepare a similar illustration of any other crop.
Answer:
a) The farmer’s income increases through the marketing of value-added products. New employment opportunities arise.

b) Pineapple jam, pineapple juice, pineapple squash, pineapple leaf fiber, pineapple wine, pineapple candy, dried pineapple pieces, pineapple vinegar, pineapple pickle.

Basic Science Class 8 Chapter 7 Question Answer Kerala Syllabus

Answers to the indicators on page no. 104
Question 1.
What are the ideas you have learned from the news reports?
Answer:

  • A school student has caught the media’s attention by developing a simple machine for harvesting cassava.
  • The little scientist has applied for a patent for his invention.
  • A young farmer with a higher degree sells banana leaves when the price of banana leaves is low.
  • He earns a good income by exploiting the market potential of nutritious leafy vegetables.
  • He earns income by making several value-added products from turmeric
  • He uniquely cultivates the rare Gandhakashala rice and markets it under a special brand, earning good sales.

Question 2.
What are the circumstances that have prompted farmers to choose new ways?
Answer:

  • The use of light machinery for harvesting cassava has made harvesting easier.
  • A unique idea that banana leaves can be sold when they are cheap.
  • Utilising the market potential of nutritious leafy vegetables.
  • Due to the fall in price of turmeric during the harvest, several value-added products have been created from turmeric and brought to the market.
  • Gandhakshala rice, which is being grown elsewhere, is being cultivated in a unique way and brought to the market under a special brand.

Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus

Question 3.
What are the other possibilities to make farming profitable?
Answer:

  • Construction of simple machines to save time and effort in farming.
  • The sale potential of not only fruits but also other parts of plants, such as leaves.
  • Value-added products from agricultural products.
  • Agricultural products are branded and marketed in a special way.
  • Growing crops that have high demand in the market.

Question 4.
Completed illustration 7.1
Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 3
Answer:
Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 4

Observe figure 7.3 (pg. no. 107) and prepare a note based on the indicators through discussion.
Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 5
Question 5.
How does it help to overcome space constraints?
Answer:
Vertical farming uses shelves or stacked layers to grow plants upwards, allowing more crops to be grown in a smaller space.

Question 6.
How does it ensure availability of light?
Answer:
The plants are arranged in such a way that all layers receive sufficient sunlight.

Question 7.
How does it help to reduce the use of water?
Answer:
Since water drips from the top layer to the bottom, many plants reuse the same water, thereby conserving it.

Question 8.
How to Control Construction Costs?
Answer:
If you use waste materials like plastic bottles, old wood, and containers, the cost is lower. Otherwise, the cost will increase.

Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus

Answers of Indicators, Page No. 108 from the Textbook
Question 9.
Macronutrients and Micronutrients:
Answer:
Plants obtain the elements they need from the soil. Of these, nitrogen, potassium, phosphorus, calcium, magnesium, and sulfur are the elements that are required in large quantities. These are called macronutrients. However, elements like barium, boron, zinc, copper, manganese, iron, molybdenum, chlorine, and nickel are required in very small quantities and are known as micronutrients.

Question 10.
Need for the application of fertilisers:
Answer:
Fertiliser is applied to ensure the availability of all the elements necessary for crops to grow.

Analysis of Table 7.1, Pg.no. 110
Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 6
Question 11.
Why is it necessary to include local vegetables in the diet?
Answer:
We can also get all the elements that plants get in various forms by consuming them. Native vegetables like Colocasia leaf, curry leaves, Drumstick leaves, and Sweet amaranth contain more protein, fiber, starch, calcium, iron, carotene, and vitamin C than other vegetables.

Question 12.
Observe the illustration 7.3 showing the methods of production of high-yield planting materials. Prepare notes on it.
Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 7
(a) Grafting

  • The process of joining the stem of one plant with the stem, including the roots, of another plant to form a single plant.
  • Used in plants such as Mango tree and roses.
  • Property: Combines the properties of both plants.

(b) Budding

  • A method of attaching a bud from one plant to the stem of another plant.
  • Used in roses, lemons, etc.
  • Advantage: Faster production

(c) Layering

  • A branch of a plant is bent to the ground and covered with soil to grow roots. Later, it is cut and planted.
  • Used in jasmine, peach, strawberry, etc.
  • Advantage: New plants are similar to the mother plant.

(d) Tissue culture

  • Seedlings are produced by isolating tissues from suitable parts of the plant and growing them in a special nutrient medium.
  • Used in bananas and orchids.
  • Benefits: Rapid production of large numbers of healthy, disease-free plants.

(e) GM crops (Genetically Modified Crops)

  • These are crops that have had their genes altered in a lab to improve their characteristics. Their production requires strict safety testing.
  • Examples: Bt cotton, golden rice.
  • Properties: Pest resistance, superior qualities, high yield.

(f) Hybridisation

  • The process of crossing two plants with different traits to produce a new plant with superior traits.
  • Used in wheat, rice, and tomatoes.
  • Advantages: High yield, disease resistance.

Figure 7.10 Cartoon Analysis on page 113
Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 8
Question 13.
What are the problems farmers face regarding water use?
Answer:
Heavy rain, floods, droughts, and water scarcity

Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus

Question 14.
What are the suggestions to solve the problems faced by farmers regarding water use?
Answer:
Water from heavy rainfall is stored in dams and reservoirs. The stored water is then transported to farmlands through systems such as canals during times of water scarcity.

Answers to the indicators on page 114
Question 15.
What are the main pests affecting crops in our region?
Answer:
Pod borer (Legume), Leaf-rolling Caterpillar (Okra), Stem Borer (Brinjal)

Question 16.
What are the various methods adopted by farmers in your area to control pests?
Answer:

  • Use of chemical pesticides
  • Use of natural enemies of pests (biological control)
  • Use of biological pesticides.
  • Farmers change the type of crop grown in a field each season. This prevents pests from multiplying because they do not get the same crop to attack each time.
  • Use of pest-resistant varieties.
  • Keeping the fields clean.
  • Weeds and debris are removed from the fields regularly. This prevents pests from hiding in the fields and breeding.

Answers to the indicators on page no. 116, by analysing illustration 7.4
Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 9
Question 17.
Integrated farming- advantages and possibilities:
Answer:
(a) Benefits of integrated farming:

  • Better use of resources.
  • No resources are wasted. Animal waste is used as fertiliser for plants. Water is reused.
  • More income for farmers
  • Farmers get income not only from crops, but also from selling milk, eggs, fish, and vegetables.
  • Even if one crop (like a bad crop) fails, other crops (like fish or eggs) provide income.

(b) The possibilities of integrated farming:

  • It can be used in villages, small farms, and even in urban areas where there is space.
  • Helps in self-employment and sustainable agriculture.
  • Promotes organic farming and protects the environment.

(c) Food security

  • Integrated farming produces non-toxic food.
  • There is less need for pesticides or artificial feed.
  • It improves nutrition for families and consumers.

(d) Reducing production costs

  • Money is saved on fertilisers and feed. Because the residue of one is used as fertiliser for the other.
  • Waste is recycled efficiently.
  • The need to buy products from outside will be reduced.

Answers to the indicators on page no. 119, based on illustration 7.6
Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 10
Question 18.
What are the benefits of diversifying agriculture?
Answer:
Agriculture is not just about producing food. Farming for Banana leaves, horticulture, Poultry farming, medicinal plant cultivation, Betel cultivation, floriculture, ornamental fish farming, and raising pets are all ways of diversifying agriculture.

Benefits:

  • More sources of income – Farmers can earn money from many activities, not just from one crop.
  • Even if one crop fails, income can be generated from other crops.
  • Efficient use of land and resources – Different activities can be done in the same area by using waste from one activity for another.
  • Employment for more people
  • Helps small families and women to get work done from home.
  • Supports local markets and economies

Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus

Question 19.
Which of these can be done even by those with limited space?
Answer:

  • Medicinal plant cultivation – on terraces, balconies or small gardens
  • Rearing of chickens – in backyards or coops
  • Ornamental fish rearing – in small tanks or containers
  • Floriculture – in pots or small plots
  • Raising of pets – at home
  • Betel cultivation – in shaded areas or along fences

Class 8 Basic Science Chapter 7 Question Answer Extended Activities

Question 1.
Find out the common plant diseases in your area. Prepare a pictorial chart listing their pathogens, mode of transmission, symptoms and remedies and display it on the bulletin board.
Answer:

Diseases Causative organism (Pathogen) Symptoms Mode of transmission Remedial measures
Blight disease in Rice Bacteria The tips of the leaves turn yellow, and the leaves become dry. Through infected seeds, rain, and wind Avoid diseased seeds.
Wilt disease in Banana Fungus The leaves turn yellow and wilt. Through soil, and through water Destroy infected plants.
Mosaic disease in Tapioca Virus Mosaic pattern on leaves Through insects Use healthy seedlings and control pests

Question 2.
Collect information about the major agricultural research institutes in Kerala and their contributions to the agricultural sector, and prepare a list of them.
Answer:

  • Kerala Agricultural University, Thrissur – Research on crops. Training for farmers
  • Indian Institute of Spices Research, Kozhikode – Research on spices like ginger, pepper and turmeric
  • Central Tuber Crops Research Institute, Thiruvananthapuram – Research on tuber crops
  • Rubber Research Institute of India, Kottayam – Production of good varieties of rubber

Question 3.
You know that many machines are used in the agricultural sector to reduce human effort. The results of thinking about how to alleviate the difficulties of farmers led to the discovery of most of the machinery seen today. Design a model of an innovative device that will be useful to the farmers in your area.
Answer:
Hint: Think about common issues experienced by small-scale farmers in a tropical, monsoon-affected area, particularly related to labor and resource management.
(An example is given below for you…)
Farmers in Kerala, particularly those cultivating crops like coconuts, spices, and various vegetables, often face challenges such as:

  • Labor Shortage & Cost
  • Nutrient Management
  • Post-Harvest Damage
  • Accessibility
  • Environmental Concerns

Device Name: Coco-Smart Harvester & Nutrient Analyzer.
The Coco-Smart Harvester & Nutrient Analyzer is a semi-autonomous, drone-based system designed to efficiently harvest tree-borne products (initially focusing on coconuts and later adaptable for other tall tree crops) while simultaneously assessing the nutrient needs of the tree/soil and delivering targeted solutions.

Operational Workflow:

  1. Pre-Flight Planning: Farmer maps out the area using a user-friendly tablet app, identifying trees for harvesting or analysis.
  2. Automated Scan & Analysis: The drone flies autonomously over the designated trees, conducting a hyperspectral scan and, if needed, deploying the soil sensor.
  3. Harvesting (if applicable): Based on visual recognition (AI-powered to identify ripe products) and farmer input, the drone’s robotic arm engages the harvesting mechanism, gently collecting the product.
  4. Nutrient Recommendation: The AI analyses the data and provides precise nutrient recommendations to the farmer’s app, indicating which trees need what specific nutrients and in what quantities.
  5. Targeted Application: The drone can then be programmed to autonomously apply the recommended nutrients via its micro-dosing sprayer or granular dispenser.
  6. Data Logging: All data (harvest quantity, nutrient status, application history) is logged for future analysis and improved farm management.

The Coco-Smart Harvester & Nutrient Analyzer aims to be a game-changer for farmers in Kerala, addressing critical challenges with a blend of robotics, AI, and precision agriculture.

Let’s Cultivate and Reap Goodness Class 8 Notes

Class 8 Basic Science Let’s Cultivate and Reap Goodness Notes Kerala Syllabus

  • Innovative agricultural initiatives can strengthen rural economies, enhance food security, and inspire future generations to engage in farming.
  • Various farming methods to make use of most of the space include sack farming, aquaponics, pet bottle farming, vertical farming, pot cultivation, and terrace farming.
  • Elements that plants need in large quantities are called macronutrients and elements that plants need in small quantities are called micronutrients.
  • Fertilisers are used to ensure the availability of all the elements that plants need to grow.
  • Different types of fertilisers used in agriculture – organic fertilisers, artificial fertilisers, nano fertilisers, and biofertilisers.
  • Grafting, budding, layering, and tissue culture are methods used to produce seedlings that have the same characteristics as the parent plant.
  • GM crops are crops that can incorporate new characteristics into crops by changing the genetic structure through genetic engineering.
  • Tissue culture is a technology that helps produce large numbers of plants that have the same characteristics as the parent plant.
  • The greenhouse is made of sheets like plastic, nylon, and polyethene. It also helps in reducing the incidence of pests and diseases as it is covered on all sides.
  • Drip irrigation is an irrigation method that uses pipes and valves to drop water into the root zone.
  • Wick irrigation is a method of delivering water directly from a water source to the root zone of plants with the help of a cotton wick.
  • Mulching is a traditional method of covering the soil in agricultural fields with leaves and straw to reduce water loss due to evaporation.
  • Integrated pest control is a method that minimises the use of pesticides through automated pest control methods using various types of nets and traps, friendly insects, and the cultivation of seeds that are resistant to pests.
  • Integrated farming is the management of diverse organisms together.
  • Smart farming is the effective use of modern technologies in agriculture, such as hydroponics, aeroponics, etc.
  • Depending on the characteristics of the land where the products are grown, there will be differences in the taste, colour, smell and nutritional value of the products. On the basis of this, agricultural products produced in some areas are given Geographical Indication (GI) status.
  • There are apps that provide weather warnings, pest and disease warnings, expert advice on agriculture, market price levels and information about benefits for farmers.

Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus

INTRODUCTION

In a world that often feels overwhelmed by challenges and negativity, the concept of “cultivating and reaping goodness” offers a powerful and hopeful perspective. This idea isn’t just a feel-good platitude; it’s a profound call to action, urging us to intentionally nurture positive qualities, actions, and intentions within ourselves and our communities. Just as a farmer carefully tends to their crops, preparing the soil, planting seeds, and providing consistent care, we too can consciously foster an environment where goodness can flourish. This process involves recognising that every small act of kindness, every moment of empathy, and every effort to uplift others contributes to a larger harvest of positive outcomes. When we actively cultivate goodness, we not only transform our own lives but also create a ripple effect, inspiring and empowering those around us to do the same. Ultimately, this journey is about understanding that the positive impact we wish to see in the world begins with the seeds we choose to plant today. In this chapter, we will deal with various agricultural initiatives, careful utilisation of land, application of fertilisers, use of high-quality planting material for getting better yield, water utilisation and pest control measures and integrated farming in detail.

AGRICULTURAL INITIATIVES

  • The ‘Karshaka Pratibha’ Puraskar is an award given by the state government to the best student farmer.
  • Innovative agricultural initiatives can strengthen rural economies, enhance food security, and inspire future generations to engage in farming.

MAXIMISING LAND UTILISATION

  • Various farming methods to make use of most of the space include sack fanning, aquaponics, pet bottle farming, vertical farming, pot cultivation, and terrace farming.
  • Vertical farming is an innovative way to overcome space constraints.

APPLICATION OF FERTILISERS

  • Elements that plants need in large quantities are called macronutrients.
  • Elements that plants need in small quantities are called micronutrients.
  • Fertilisers are used to ensure the availability of all the elements that plants need to grow.
  • Different types of fertilisers used in agriculture – organic fertilisers, artificial fertilisers, nano fertilisers, and biofertilisers.

Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus 11

  • All the elements that plants get are also available to us as food in various forms.
  • Native varieties will grow in harmony with the local environment.

FOR BETTER YIELD, HIGH QUALITY PLANTING MATERIALS

  • Grafting, budding, layering, and tissue culture are methods used to produce seedlings that have the same characteristics as the parent plant.
  • GM crops are crops that can incorporate new characteristics into crops by changing the genetic structure through genetic engineering.
  • Tissue culture is a technology that helps produce large numbers of plants that have the same characteristics as the parent plant.

UTILISATION OF WATER AND PEST CONTROL
UTILISATION OF WATER

  • A greenhouse is a system that helps in cultivating crops both in the rainy season and in the summer.
  • Drip irrigation is an irrigation method that uses pipes and valves to drop water into the root zone.
  • Wick irrigation is a method of delivering water directly from a water source to the root zone of plants with the help of a cotton wick.
  • Mulching is a traditional method of covering the soil in agricultural fields with leaves and straw to reduce water loss due to evaporation.

Let’s Cultivate and Reap Goodness Class 8 Questions and Answers Notes Basic Science Chapter 7 Kerala Syllabus

PEST CONTROL

  • Although there are different methods for pest control, the population density of pests and the nature off the crops should be taken into account when choosing the pest control methods.
  • Farmers do not want to kill all the pests, but rather control their growth in a way that does not damage the crops.
  • Integrated pest control is a method that minimises the use of pesticides through automated pest control methods using various types of nets and traps, friendly insects, and the cultivation of seeds that are resistant to pests.

INTEGRATED FARMING

  • Integrated farming is the management of diverse organisms together.
  • Smart farming is the effective use of modern technologies in agriculture.
  • Hydroponics – Plants are grown in nutrient solutions, and the amount of nutrients is detected with the help of sensors and provided as needed.
  • Aeroponics – Water and nutrients are provided to the roots growing in the air in a timely manner with the help of sensors.
  • If a system is set up for consumers to see the process from sowing to harvesting, the reliability and market value of the products can be increased.
  • Depending on the characteristics of the land where the products are grown, there will be differences in the taste, colour, smell and nutritional value of the products. On the basis of this, agricultural products produced in some areas are given Geographical Indication (GI) status.
  • Agriculture is not only about producing food.
  • There are apps that provide weather warnings, pest and disease warnings, expert advice on agriculture, market price levels and information about benefits for farmers.

ഭഗീരഥപ്രയത്നം Notes Question Answer Class 8 Adisthana Padavali Chapter 9

Practicing with Std 8 Malayalam Adisthana Padavali Notes Unit 3 Chapter 9 ഭഗീരഥപ്രയത്നം Bhagiratha Prayatnam Notes Questions and Answers Pdf improves language skills.

ഭഗീരഥപ്രയത്നം Question Answer Notes Std 8 Malayalam Adisthana Padavali Chapter 9

Class 8 Malayalam Adisthana Padavali Unit 3 Chapter 9 Notes Question Answer Bhagiratha Prayatnam

Class 8 Malayalam Bhagiratha Prayatnam Notes Questions and Answers

പാഠപുസ്തകത്തിലെ ചോദ്യങ്ങളും ഉത്തരങ്ങളും

ബന്ധം കണ്ടെത്തുക

Question 1.
“ഉത്തമരാവട്ടെ നിരന്തരം വിഘ്നമുണ്ടായാലും തുടങ്ങിയ കാര്യത്തിൽ നിന്ന് ഒരിക്കലും മാറുന്നില്ല.” നീതിശതകത്തിലെ ഈ വാക്യം പാഠഭാഗവുമായി ബന്ധപ്പെട്ടിരിക്കുന്നതെങ്ങനെ? വിശദമാക്കുക.
Answer:
നീചർ വിഘ്നങ്ങളുണ്ടാകുമെന്ന ഭയത്തിൽ ഒന്നും തുടങ്ങാറില്ല,
മധ്യമർ തുടക്കം ചെയ്തു വിഘ്നം വരുമ്പോൾ ഉപേക്ഷിക്കും,
ഉത്തമർ പലതവണ വിഘ്നങ്ങൾ വന്നാലും പിന്മാറാതെ ശ്രമിക്കുമെന്ന

ഭർത്തൃഹരിയുടെ **’നീതിശതക’** ത്തിലെ ഈ ശ്ലോകം “ഭഗീരഥപ്രയത്നം” എന്ന പാഠഭാഗവുമായി അതിവിശിഷ്ടമായി ബന്ധപ്പെട്ടിരിക്കുന്നു.

വാൽവ് നിർമ്മാണത്തിലെ നിരന്തരമായ പരാജയങ്ങളും നിരാശകളും അതിജീവിച്ച് വിജയത്തിലേക്ക് നയിച്ച ഡോ. എം.എസ്. വല്യത്താൻ എന്ന ശാസ്ത്രജ്ഞന്റെ ജീവിതകഥയാണ് ഈ പാഠഭാഗം.

അദ്ദേഹം പലതവണ പരാജയപ്പെട്ടിട്ടും ശ്രമം നിർത്തിയില്ല. പൊതുസമൂഹത്തിലെ, തിരസ്കാരം, അപഹാസ്യം – എല്ലാം സഹിച്ചും ലക്ഷ്യത്തിലേക്ക് മുന്നേറി.

ഇത് അദ്ദേഹത്തെ ഉത്തമനായി ലോകത്തിൽ ചിത്രീകരിക്കുന്നവരുമായും ഭഗീരഥനുമായും ബന്ധിപ്പിക്കുന്നു.

പാഠത്തിലെ സന്ദേശം അതിലൂന്നിയതായും ആ ശ്ലോകം അതിന്റെ ആന്തരവായനയായും വരുന്നു. വിജയത്തിലേക്കുള്ള മാർഗം നിശ്ചയദാർഢ്യത്തിലൂടെ പോകുന്ന കഠിനമായ പാത ആണെന്നത് ഇരുവരും പറയുന്നുണ്ട്.

ഭഗീരഥപ്രയത്നം Notes Question Answer Class 8 Adisthana Padavali Chapter 9

ശൈലീനിഘണ്ടു തയ്യാറാക്കാം

Question 1.
ഭഗീരഥപ്രയത്നം – കഠിനമായ പരിശ്രമം
ഇത്തരത്തിലുള്ള കൂടുതൽ ശൈലികൾ ശേഖരിച്ച് ഒരു ലഘുശൈലീ നിഘണ്ടു തയ്യാറാക്കുക.
Answer:
ശൈലികളും അർത്ഥങ്ങളും

  1. ഭഗീരഥപ്രയത്നം = കഠിനമായ ദീർഘകാല പരിശ്രമം
  2. വിസ്മയവൃക്ഷം = അപൂർവ പ്രതിഭ / തൽക്കാലത്തിൽ കണ്ടുകിട്ടാത്തത്
  3. പഞ്ചപാണ്ഡവർ = ശക്തമായ കൂട്ടം / അഞ്ചംഗ സംഘം
  4. കുതിരക്കണ്ണി പോലെ = ഒറ്റദിശയിലേയ്ക്ക് മാത്രം ശ്രദ്ധ കേന്ദ്രീകരിക്കുക
  5. വടംവലി = ശക്തിപോരാട്ടം/രണ്ടുവശത്തിനും തല്ല് നടക്കുന്നത്
  6. മനസ്സാക്ഷിയുടെ ശബ്ദം = ആഭ്യന്തര താരതമ്യം/സത്യബോധം
  7. ആരു പാടുന്നു അയ്യപ്പൻ പാട്ട്! = വിഷയവുമായി ബന്ധമില്ലാതെ ഇടപെടൽ കാണിക്കുമ്പോൾ
  8. കുപ്പായം മാറിയാലും സ്വഭാവം മാറില്ല. = രൂപം മാറിയാലും സ്വഭാവം മാറില്ല

പ്രഭാഷണം

Question 1.
നിശ്ചയദാർഢ്യവും ആത്മവിശ്വാസവും നമ്മെ ഉയർച്ചയുടെ പടവുകൾ താണ്ടാൻ സഹായിക്കും. ‘ജീവിതവിജയം നിശ്ചയദാർഢ്യത്തിലൂടെ’ എന്ന വിഷയത്തിൽ ഒരു പ്രഭാഷണം തയ്യാറാക്കുക.
Answer:
ആദരണീയരായ അധ്യാപകരെ പ്രിയപ്പെട്ട കൂട്ടുകാരെ നമസ്കാരം,

ജീവിതത്തിൽ വിജയിക്കണമെന്ന് ആഗ്രഹിക്കാത്തവരുണ്ടാകില്ല. എന്നാൽ ആ വിജയത്തേക്കുള്ള വഴി പുഷ്പപന്തലുകൾ കിടക്കുന്ന ഒരു പാതയല്ല. അതു കല്ലുകളും വിഘ്നങ്ങളും നിറഞ്ഞ കഠിനമായ ഒരു യാത്രയാകാം.

ഇത്തരമൊരു വഴിയിൽ നമ്മെ ഉറച്ചപാദത്തോടെ നയിക്കുന്നത് നിശ്ചയദാർഢ്യവും ആത്മവിശ്വാസവുമാണ്.

‘ഭഗീരഥപ്രയത്നം’ എന്ന കഥയിൽ നമ്മൾ കണ്ടത്, ഡോ. എം.എസ്. വല്യത്താൻ എന്ന ശാസ്ത്രജ്ഞന്റെ ഉദാത്തമായ കഠിന പരിശ്രമമാണ്. ഏഴുവർഷത്തെ നിരന്തരമായ പരാജയങ്ങൾക്കിടയിലും, രാഷ്ട്രീയ സാമൂഹിക സമ്മർദ്ദങ്ങൾക്കിടയിലും, അവഹേളനങ്ങളിടയിലും അദ്ദേഹം പിന്തിരിഞ്ഞില്ല. കാരണം അദ്ദേഹത്തിന് വിശ്വാസം ഉണ്ടായിരുന്നു, തന്റെ കഴിവിലും ലക്ഷ്യത്തിലും.

നിശ്ചയദാർഢ്യം എന്നാൽ ചോദ്യങ്ങളെ അവഹേളിച്ച് മുന്നേറുക അല്ല, മറിച്ച് ചോദ്യങ്ങൾക്കിടയിലും ദൃഢമായി താൻ ചെയ്യുന്ന പ്രവർത്തിയിൽ പൂർണ്ണമായും വിശ്വസിച്ച് മുന്നേറുകയാണ്.

ആത്മവിശ്വാസം എന്നാൽ എല്ലാ പ്രോത്സാഹനവും കിട്ടുമ്പോൾ മാത്രം നിലനിൽക്കുന്ന വിശ്വാസം അല്ല, മറിച്ച് ചുറ്റിലും നിരാശയും, പിന്തിരിപ്പൻ ചിന്താഗതികളും പറയുന്ന എതിരാളികൾക്കിടയിലും നിലനിൽക്കുന്ന വിശ്വാസം ആണ്.

ഇന്ന് ലോകം ചിന്തിക്കുന്നതിലും മുന്നിലാണ് ഇന്ത്യയുടെ ശാസ്ത്രം. എന്നാൽ ആ വിജയങ്ങളുടെ മുൻകഥകളിൽ ധാരാളം പൊളിഞ്ഞ പരീക്ഷണങ്ങളാണ്, പരാജിതമായ മോഡലുകളാണ്, തള്ളി പറഞ്ഞു കളഞ്ഞ ആശയങ്ങളാണ്. അതിനെ അതിജീവിച്ചത് നിശ്ചയദാർഢ്യമാണ്.

അവസാനമായി ഞാൻ ഓർമ്മിപ്പിക്കുന്നു, വിജയം ഒരു ലക്ഷ്യമാണ്, പക്ഷേ അതിലേക്ക് എത്തിക്കാനുള്ള ചതുപ്പുതടങ്ങൾ കടക്കേണ്ടത് നമ്മുടെ മനസ്സിന്റെ ഉറപ്പുകൊണ്ടാണ്. നമുക്ക് ഓർക്കാൻ പിന്തുടരാൻ ഒരുപാട് വിജയഗാഥകൾ ഉണ്ടല്ലോ.. “വിളക്ക് കൈവശമുള്ളവനെങ്ങും വിശ്വം ദീപമയം” അറിവുള്ളവനെന്നും അത്മവിശ്വാസമുള്ളവനായിരിക്കും അതുകൊണ്ട് നേടുക ആത്മവിശ്വാസത്തോടെ മുന്നേറുക നന്ദി നമസ്കാരം.

തുടർപ്രവർത്തനങ്ങൾ

Question 1.
വാൽവ് വിജയകരമായി പ്രവർത്തിക്കുന്നതായി എങ്ങനെ ഉറപ്പിച്ചു?
Answer:
വാൽവിന്റെ പ്രവർത്തനം വിജയകരമാണെന്ന് ഉറപ്പാക്കാൻ പരീക്ഷണങ്ങളാണ് നടത്തിയത്. ആദ്യമായി വാൽവ് ഘടിപ്പിച്ചപ്പോൾ അത് ശരിയായി പ്രവർത്തിച്ചില്ലെങ്കിലും, പിന്നീട് പലതവണ വീണ്ടുചേർക്കലുകൾ നടത്തി പ്രവർത്തന പരിശോധന നടത്തിയപ്പോഴാണ് അതിന്റെ പ്രവർത്തനവിജയം ഉറപ്പാക്കിയത്. വാൽവിന്റെ വിജയകരമായ പ്രവർത്തനം ഉറപ്പാക്കാൻ നടത്തിയ പരീക്ഷണങ്ങളാണ് പ്രധാനമായും ശ്രദ്ധേയമായത്. ആരംഭത്തിൽ ഒന്നിലധികം തവണ പരാജയപ്പെട്ടെങ്കിലും, അവയെ പഠനോപാധിയായി കാണുകയും ഓരോ പരാജയത്തെയും അടുത്ത പരീക്ഷണത്തിനുള്ള മുന്നൊരുക്കമായി ഉപയോഗിക്കുകയും ചെയ്തു. പിന്നീട് നിർമ്മിച്ച വാൽവ് ഘടിപ്പിച്ച ശേഷം നടത്തിയ പരീക്ഷണങ്ങളിൽ വായുവിന്റെ ചോർച്ച ഇല്ലാതെയും നിയന്ത്രിത സവം സാധ്യമാകുന്നതായും കണ്ടപ്പോൾ അതിന്റെ വിജയകരമായ പ്രവർത്തനം സ്ഥിരീകരിച്ചു. വായു സ്രവം നിയന്ത്രിക്കാൻ വാൽവിന് കഴിഞ്ഞത് ഈ വിജയത്തിന്റെ സൂചനയായി എഴുത്തുകാരൻ വ്യക്തമാക്കുന്നു.

Question 2.
നീതിശതകം – എന്ന കൃതിയുടെ രചയിതാവ് ആരാണ്?
Answer:
‘നീതിശതകം’ എന്ന പൗരസ്ത്യ സൗന്ദര്യപൂർണതയുള്ള ധർമ്മബോധപരമായ ശ്ലോകസമാഹാരത്തിന്റെ രചയിതാവ് ഭർത്തൃഹരി ആണ്. ഭർതൃഹരിയുടെ മൂന്നു ശതകങ്ങളിൽ ഒന്നായ നീതിശതകം മനുഷ്യജീവിതത്തിലെ നിത്യേന അഭിമുഖീകരിക്കേണ്ട ആചാരാനുശാസനങ്ങളെയും മൂല്യബോധത്തെയും അടിസ്ഥാനമാക്കിയാണ് എഴുതപ്പെട്ടത്. ഈ ഗ്രന്ഥത്തിൽ ഉപദേശപരമായ നിരവധി ശ്ലോകങ്ങൾ ഉൾക്കൊള്ളുന്നു അതിലെ ശ്ലോകങ്ങളിലൂടെയാണ് ലേഖനത്തിൽ ഉദാഹരണങ്ങൾ നൽകുന്നത്, പ്രത്യേകിച്ച് പരാജയത്തെ കുറിച്ചുള്ള ആഴമുള്ള സൂചന നൽകുന്നുണ്ട്.. ലേഖനത്തിൽ ഉൾപ്പെടുത്തിയിരിക്കുന്ന ഈ കൃതിയിലെ ശ്ലോകം – ‘പരാജയത്തിന്റെ ഭയം തോൽവിയുടെ പ്രധാനകാരണം ആകുന്നു’ എന്നതിനുള്ള സൂചന നൽകുന്ന ഉദാഹരണമായി ഉപയോഗിച്ചിരിക്കുന്നു. അതുവഴി, വിജയം നേടാൻ ഭയം ഒഴിവാക്കേണ്ടതും പ്രതീക്ഷയും ആത്മവിശ്വാസവുമുള്ള സമീപനമാണ് വേണ്ടതെന്നും ലേഖകൻ ഉപദേശിക്കുന്നു.

Question 3.
വാൽവ് വികസനത്തിൽ ആദ്യ വർഷങ്ങളിൽ ലഭിച്ച എതിരഭിപ്രായങ്ങളെ എഴുത്തുകാരൻ എങ്ങനെ ഏറ്റെടുത്തു?
Answer:
ആദ്യകാല പരീക്ഷണങ്ങളിൽ എഴുത്തുകാരൻറെ ആശയത്തെ ചൊല്ലി അധ്യാപകരിൽ നിന്നും സഹപാഠികളിൽ നിന്നുമുണ്ടായ എതിരഭിപ്രായങ്ങൾ അദ്ദേഹത്തെ തളർത്തിയില്ല. മറിച്ച്, അവയെ ചിന്താപരമായ വെല്ലുവിളികളായി കാണുകയും,തെറ്റുകൾ തിരുത്തി, മാതൃക മെച്ചപ്പെടുത്തുകയും, പരാജയങ്ങളെ പഠനമായി മാറ്റുകയും ചെയ്തു. ഇത് ശാസ്ത്രീയ സമീപനത്തിന്റെ മികച്ച ഉദാഹരണമാണ്. ലക്ഷ്യത്തിൽ ഉറച്ച നിലപാടും ആത്മവിശ്വാസവും കൊണ്ടാണ് അദ്ദേഹം ഈ വിചാരങ്ങളെ ചെറുത്തത്. ഈ സമീപനം തന്നെയാണ് വിജയം കൈവരിക്കാൻ അടിയന്തരമായി വേണ്ട പ്രധാന ഗുണം, അതായത് നൈരാശ്യത്തിൽ മുക്കിയല്ല, പ്രതിസന്ധികളെ അതിജീവിച്ചാണ് വിജയം എത്തിപ്പെടുന്നത്.

ഭഗീരഥപ്രയത്നം Notes Question Answer Class 8 Adisthana Padavali Chapter 9

Question 4.
‘ഭഗീരഥപ്രയത്നം’ എന്ന ശീർഷകം ഈ ലേഖനത്തിന് എങ്ങനെ യോജിക്കുന്നു?
Answer:
ഭഗീരഥൻ ഗംഗയെ ഭൂമിയിലെത്തിക്കാൻ നടത്തിയ അതിസാഹസികവും,ദീർഘകാലമുള്ളതുമായ, അതിയായ പരിശ്രമം പോലെയാണ് എഴുത്തുകാരൻ തന്റെ വാൽവ് ആവിഷ്കൃതിയിൽ നടത്തിയ കഠിനപ്രയത്നം. ലേഖകൻ തന്റെ ആശയമായ വാൽവിന്റെ ആവിഷ്ക്കരണം വിജയിപ്പിക്കാൻ നടത്തിയ ശ്രമം ‘ഭഗീരഥപ്രയത്ന’ ത്തെ അനുസ്മരിപ്പിക്കുന്നു. എത്രയോ പ്രയാസങ്ങൾക്കുമേൽ കയറി, നിരന്തരമായി പരാജയങ്ങൾ ഏറ്റുവാങ്ങിയെങ്കിലും, പ്രതീക്ഷയും അച്ചടക്കവും കൈവിടാതെ സാങ്കേതികമായ വിജയം നേടിയ അനുഭവം ഈ ശീർഷകത്തോട് പൊരുത്തപ്പെടുന്നതാണ്. അതുകൊണ്ടുതന്നെ ‘ഭഗീരഥപ്രയത്നം’ എന്നത് ലേഖനത്തിന്റെ ഉള്ളടക്കത്തെയും ആത്മാവിനെയും പ്രസന്നമാക്കുന്ന ഉചിതമായ ശീർഷകമായി മാറുന്നു.ഈ ശീർഷകം ഈ കണ്ടെത്തലിനു പിന്നിലെ ത്യാഗം, സ്ഥിരത, ഉറച്ച മനസ്സുള്ള ശ്രമം എന്നിവയെ യോജിപ്പിക്കുകയാണ്.

Question 5.
ശാസ്ത്രസംരംഭങ്ങളിൽ പരാജയങ്ങൾ എങ്ങിനെയാണ് വിജയം ആയി മാറുന്നതെന്ന് എഴുത്തുകാരൻ വിശദീകരിക്കുന്നു?
Answer:
എഴുത്തുകാരൻ പറയുന്നു, ഓരോ പരാജയവും വിജയത്തിലേക്ക് കടക്കാനുള്ള പാതയിലെ ഒരു പാഠമാണ്. പരാജയത്തെ ഭയപ്പെടാതെ, അതിൽ നിന്നും പഠിച്ച്, തുടർച്ചയായ പരിശ്രമത്തിലൂടെ വിജയമൊരുക്കാനാവുമെന്ന് അദ്ദേഹം തന്റെ അനുഭവം മുഖേന വ്യക്തമാക്കുന്നു. അതുപോലെ, ശാസ്ത്രജ്ഞന്മാരുടെയും നിർമാതാക്കളുടെയും ജീവിതത്തിൽ ഓരോ വലിയ വിജയത്തിനും പിന്നിൽ നിരവധി പരാജയങ്ങളും നഷ്ടങ്ങളും ഉണ്ടായിട്ടുണ്ട്. എഴുത്തുകാരൻ തന്റെ ജീവിതാനുഭവത്തിലൂടെ ഇതെല്ലാം ആവിഷ്കരിക്കുകയും, ശാസ്ത്രസംരംഭങ്ങളിൽ ആത്മവിശ്വാസം, ചിരകാല പരിശ്രമം, നിരന്തരപരിശോധന എന്നിവയിലൂടെ പരാജയം പോലും വിജയം ആകാമെന്ന് തെളിയിക്കുന്നു. ലേഖകൻ പറഞ്ഞിരിക്കുന്ന പോലെ, വിജയം കൈവരിക്കാൻ നിർഭാഗ്യങ്ങൾ അതിജീവിക്കേണ്ടി വരും. വ്യക്തമായ ലക്ഷ്യബോധവും കഠിനപ്രവൃത്തിയും സഹിച്ചാൽ, നമുക്ക് കഴിവുകളിൽ കൂടുതൽ നേടി ഉയരങ്ങളി ലെത്താനാകും. അനുകൂലതകളും പ്രതികൂലതകളും ജീവിതത്തിന്റെ ഭാഗങ്ങളാണ് എന്ന തിരിച്ചറിവ്, ജീവിതത്തോടുള്ള മനോഭാവം മെച്ചപ്പെടുത്തുന്നു.

Question 6.
നിങ്ങളുടെ ചുറ്റുപാടുകളിൽ പരാജയത്തിനുശേഷം വിജയം നേടിയ ഏതെങ്കിലും സന്ദർഭങ്ങൾ അനുഭവക്കുറിപ്പായി എഴുതുക.
Answer:
എട്ടാം ക്ലാസിൽ നടന്ന ശാസ്ത്രമേളയിൽ അണക്കെട്ടിന്റെ ആധുനിക മോഡൽ തയ്യാറാക്കിയിരുന്നു. ഞാൻ ആദ്യം തയ്യാറാക്കിയ മോഡൽ വെള്ളം ചോരുന്ന കാരണത്തെ കൊണ്ട് തള്ളപ്പെട്ടു. പക്ഷേ, അത് പരിഹരിച്ച് മെച്ചപ്പെട്ട സാധനങ്ങൾ ഉപയോഗിച്ച് വീണ്ടും തയ്യാറാക്കി രണ്ടാം ദിവസം പരീക്ഷിച്ചപ്പോൾ അത് വിജയകരമായി പ്രവർത്തിച്ചു. അദ്ധ്യാപകരും സഹപാഠികളും അഭിനന്ദിച്ചപ്പോൾ വലിയ സന്തോഷം അനുഭവപ്പെട്ടു. ഈ സംഭവത്തിൽ നിന്ന് പഠിച്ചത്. ശ്രമം അവസാനിക്കാതെ തുടരുക.

Question 7.
ലേഖകന്റെ അനുഭവം നമ്മുടെ ജീവിതം വിജയകരമാക്കാൻ എന്തെല്ലാം പാഠങ്ങൾ നല്കുന്നു.
Answer:
പുതിയ ആശയങ്ങൾ പരീക്ഷിക്കുമ്പോൾ പരാജയം ഒന്നും അപമാനകരമായ ഒന്നല്ലെന്ന് ലേഖകൻ വ്യക്തമാക്കുന്നു. മറിച്ച്, പരാജയം വിജയത്തിലേക്കുള്ള അടുത്ത ചുവടായി അദ്ദേഹം കാണുന്നു. ഓരോ പരാജയവും അടുത്ത പരീക്ഷണത്തിന് പുതിയ അറിവ് നൽകുന്നു, തെറ്റുകൾ തിരിച്ചറിയാൻ സഹായിക്കുന്നു. അദ്ദേഹം നിർമ്മിച്ച ആദ്യകാല വാൽവുകൾ കാര്യക്ഷമമായി പ്രവർത്തിച്ചില്ലെങ്കിലും, ആ പരാജയങ്ങൾ പഠനത്തിനും സാങ്കേതിക പരിഷ്കരണത്തിനും വഴിയൊരുക്കി. ലേഖകൻ പങ്കുവെക്കുന്ന വാൽവ് വികസന അനുഭവം നമ്മെ ഈ സത്യം ബോധ്യപ്പെടുത്തുന്നു. ആദ്യത്തിൽ അദ്ദേഹം നേരിട്ട പരീക്ഷണങ്ങൾ, പരാജയങ്ങൾ, പരിഹാസങ്ങൾ തുടങ്ങിയവ സ്വാഭാവികമായാണ് സംഭവിച്ചത്. എന്നാൽ അദ്ദേഹം അവയെ കുഴപ്പമായി കാണാതെ, ഓരോ പരാജയവും വിജയത്തിലേക്കുള്ള പടിയെന്ന നിലയിലാണ് സമീപിച്ചത്. ഈ മനോഭാവം ജീവിതത്തിലെ എല്ലാ മേഖലയിലും അത്രയും പ്രസക്തമാണ്.

നാം വിദ്യാർത്ഥികളായി പഠനത്തിൽ, തന്ത്രപരമായ പ്രവർത്തനങ്ങളിൽ, സ്വാഭാവിക ജീവിതത്തിലുമൊക്കെ നിരവധി തോൽവികൾക്ക് ശില്പികളാവേണ്ടി വരും. അവയെ കുറിച്ചുള്ള നമ്മുടെ സമീപനം നമ്മുടെ വിജയത്തിന്റെ ദിശ നിർണയിക്കും. എഴുത്തുകാരനെ പോലെ നാം ധൈര്യത്തോടെയും സ്ഥിരതയോടെയും മുന്നോട്ടുപോകണം. ജീവിതം വെറുമൊരു വിജയയാത്രയല്ല; പരീക്ഷണങ്ങൾ നിറഞ്ഞ വഴിയിലാണ് അത് നടക്കുന്നത്. അവയെ അതിജീവിക്കാനും അതിൽ നിന്ന് ഉയരാനും നമുക്ക് ഈ അനുഭവം ഏറെ പാഠങ്ങൾ നൽകുന്നു.

Question 8.
മനസ്സിൽ നൈരാശ്യമെഴുന്നവന്നു
മധ്യാഹ്നവും പ്രത്യഹമർധരാത്രം;
ശുഭം പ്രതീക്ഷിച്ചവനേതു രാവും
സൂര്യാംശുദീപം പകൽപോലെതന്നെ
– ഉള്ളൂർ
ഉള്ളൂരിന്റെ ഈ കവിതയും ഭഗീരത പ്രയത്നത്തെയും താരതമ്യചെയ്തുക്കുറിപ്പ് തയ്യാറാക്കുക.
Answer:
ഉള്ളൂർ ഈ കവിതയിൽ മനുഷ്യന്റെ ആത്മവിശ്വാസം, പ്രതീക്ഷയുടെ ശക്തി എന്നിവയിലൂടെ എത്രമാത്രം അഗാധമായ ദൗർബല്യവും മറികടക്കാമെന്ന് കാണിക്കുന്നു. അർദ്ധരാത്രിയും മധ്യാഹ്നം പോലെ പ്രതീ ക്ഷയുടെ പ്രകാശം കൊണ്ട് നിറയ്ക്കാൻ കഴിയുമെന്ന് കവി പറയുന്നു. അതുപോലെ, ലേഖനത്തിൽ വാൽവ് ആവിഷ്ക്കാരം വഴി എഴുത്തുകാരൻ പ്രത്യക്ഷപ്പെടുത്തിയത് സ്ഥിരതയുള്ള ശ്രമത്തിലൂടെ വിജയമെന്ന പ്രതീക്ഷ സാക്ഷാത്കരിക്കാമെന്നത് തന്നെയാണ്. ഇരുപേരുടെയും കൃതികളിലും പ്രതീക്ഷയും പരിശ്രമവും മുഖ്യമാകുന്നു ജീവിതം പലപ്പോഴും പ്രതീക്ഷകൾക്ക് വിരുദ്ധമായ വഴികളിലൂടെ നമ്മെ നയിക്കുന്നു. ഇത്തരം സാഹചര്യങ്ങളിൽ പതറാതിരിക്കാൻ വേണ്ടത് ആത്മവിശ്വാസവും സംയമനവുമാണ്.

ഉള്ളൂർ എഴുതിയ കാവ്യം പ്രതീക്ഷയുടെ സാക്ഷിയാകുന്നു. “മനസ്സിൽ നൈരാശ്യമെഴുന്നവന്നു…’ പകൽ പോലും അർദ്ധരാത്രി ആയിട്ട് പ്രതീകമാവുകയും വിളക്ക് കൈവശം ഉള്ളവന് അഥവാ ശുഭാപ്തി വിശ്വാസം ഉള്ളവന് ഈ ശ്ലോകത്തിൽ അർദ്ധരാത്രിയും നട്ടുച്ച പോലെ പ്രകാശപൂരിതമായിരിക്കും എന്നാണ് പറയുന്നത്. പ്രതീക്ഷ നിലനിർത്തുന്ന മനുഷ്യനെക്കുറിച്ചാണ് ഉള്ളൂർ സംസാരിക്കുന്നത്. അതുപോലെ, ഭഗീരത പ്രയത്നം’ എന്ന ലേഖനത്തിലെ എഴുത്തുകാരൻ തന്റെ ആശയ സാക്ഷാൽക്കരണത്തിനായി അപാരമായ കഠിനപ്രയത്നം നടത്തുന്നു. ഇരുവരുടെയും സൃഷ്ടിയിൽ നമുക്ക് പ്രത്യക്ഷമാകുന്നത് നൈരാശ്യത്തെ മറികടക്കുന്ന മനുഷ്യന്റെ ആത്മശക്തിയും ആത്മവിശ്വാസവും ആണ്.

കവിതയിൽ, പ്രതീക്ഷ പ്രകാശം പോലെയും പകൽപോലെയും ശക്തിയായി പ്രത്യക്ഷപ്പെടുന്നു. ലേഖനത്തിൽ, നിർമിച്ച വാൽവ് വിജയകരമായി പ്രവർത്തിക്കുന്നവരെക്കുറിച്ചുള്ള വ്യക്തതയും അതിനു പിന്നിൽ നിലകൊണ്ട് ആത്മാർത്ഥതയും പറയുന്നു. ഈ രണ്ടിലും ഒത്തു ചേരുന്നത് മനുഷ്യന്റെ ആത്മശ്രദ്ധയും വിശ്വാസവുമാണ്, ഉദ്യമം എത്ര കഠിനമായാലും പിന്മാറാതെ നിലകൊള്ളുന്ന ആത്മവീര്യം. അതുകൊണ്ടുതന്നെ ഈ രണ്ട് രചനകളും മനുഷ്യജീവിതത്തിൽ പ്രതീക്ഷയുടെ പോഷകമാകുന്ന പാഠങ്ങളാണ് നൽകുന്നത്.

ഭഗീരഥപ്രയത്നം Notes Question Answer Class 8 Adisthana Padavali Chapter 9

പഠനം സഫലം

പ്രതികരണക്കുറിപ്പ്

Question 1.
കണ്ടും കേട്ടും അറിഞ്ഞും അനുഭവിച്ചും പഠിക്കുമ്പോഴാണ് അറവ് പൂർണ്ണതയിലെത്തുക എന്ന ആശ യത്തോടുള്ള നിങ്ങളുടെ പ്രതികരണം കുറിയ്ക്കു.
Answer:
“അറിവ് പൂർണ്ണതയിലെത്തുന്നത് കണ്ട്, കേട്ട്, അറിഞ്ഞ്, അനുഭവിച്ചാണ്.”
ഡോ. പി.കെ. വാരിയർ എഴുതിയ ‘പഠനം സഫലം’ എന്ന ലേഖനത്തിൽ ഉയർത്തുന്ന ഏറ്റവും പ്രധാനപ്പെട്ട സന്ദേശം ഈ ഉദ്ധരണിയിൽ തന്നെ ഉൾക്കൊള്ളുന്നു. അറിവ് നേടുന്നത് ഒരു ദീർഘകാല ശ്രമത്തിന്റെ ഫലമാണ് പുസ്തകങ്ങളിൽ നിന്നും മാത്രമല്ല,

ജീവിതാനുഭവങ്ങളിൽ നിന്നും കൂടി ആ അറിവ് തികഞ്ഞ് പാകപ്പെടണം

വൈദ്യവിദ്യാഭ്യാസത്തിന്റെ പരമ്പരാഗത മാതൃകയായ “ഏതിൽ പത്ത് കാട്ടിൽ പത്ത് നാട്ടിൽ പത്ത്” എന്നത് ഈ ആശയത്തെ വ്യക്തമായി വിവരിക്കുന്നു. ആദ്യ പത്തു വർഷം പുസ്തകങ്ങളിലൂടെ (ഏടുകൾ) അറിവ് സമ്പാദിക്കുന്നു അതിൽ കണ്ടും കേട്ടും പഠിക്കുക. തുടർന്ന്, മരുന്നുകളുടെ സ്വഭാവം പ്രകൃതിയിൽ നേരിൽ കണ്ട് പഠിക്കുന്നു അറിയൽ ഇവിടെ ആഴപ്പെടുന്നു. അതിനുശേഷം, വൃദ്ധനായ ഗുരുവിൻറെ കീഴിൽ രോഗികളെ നേരിൽ കണ്ടും ചികിത്സിച്ചും അനുഭവിച്ചും അറിവ് കരസ്ഥമാക്കുന്നു. അങ്ങനെയാണ് ഒരാളുടെ പഠനം പൂർണ്ണമാകുന്നത്.

ഇന്നത്തെ വിദ്യാഭ്യാസ സാഹചര്യങ്ങളിൽ പലരും ‘പുസ്തകപഠന’ത്തിൽ മാത്രം തെളിഞ്ഞു പോകുകയാണ്. പരീക്ഷാനിലവാരത്തിൽ മാത്രം ശ്രദ്ധകേന്ദ്രീകരിച്ച്, ജീവിതാനുഭവങ്ങൾക്കൊന്നും പ്രാധാന്യം കൊടുക്കാതെ കടന്നുപോകുന്നു. എന്നാൽ, ഒരാൾക്ക് യഥാർത്ഥ അറിവ് പകർന്നു നൽകുന്നത് ജീവിതം എന്ന അധ്യാപകനാണ്.

വിദ്യാർത്ഥിയായ എനിക്ക്, ഈ ലേഖനത്തിൽ നിന്നുള്ള ഏറ്റവും ശക്തമായ ബോധം ഇതാണ് ഓരോ അധ്യായവും ഒരു പടി മാത്രമാണ്. അതിന് പുറമെ, മനുഷ്യരുമായി ബന്ധപ്പെടൽ, പരീക്ഷണങ്ങൾ, ജീവിതം നേരിൽ കാണുന്ന അനുഭവങ്ങൾ, വയസ്സിനും പരിചയത്തിനും നൽകിയ ആദരവ്, ഇവയൊക്കെ ഒരുപാട് പ്രധാനപ്പെട്ടവയാണ്.

അതിനാൽ, ഞാനുറപ്പായി വിശ്വസിക്കുന്നു കണ്ടും കേട്ടും അറിഞ്ഞും അനുഭവിച്ചും ഒരുമിച്ചു പഠിക്കുമ്പോഴാണ് അറിവ് തീർത്തും പൂർണ്ണമാകുന്നത്. അതിലാണ് ശാശ്വതമായ വിജയം നിലകൊള്ളുന്നത് എന്ന്.

Question 2.
കൂട്ടുകാരെ ചോദ്യപേപ്പറിൽ വരുന്ന കത്തെഴുതുക, നിവേദനം തയ്യാറാക്കുക, പത്രവാർത്ത തയ്യാറാക്കുക, ഡയറിക്കുറിപ്പ് എഴുതുക തുടങ്ങിയ ചോദ്യങ്ങൾക്ക് ഉത്തരമെഴുതുമ്പോൾ മുഴുവൻ മാർക്കും ലഭിക്കുന്നതിന് ആവശ്യമായ കുറച്ചു നിർദ്ദേശങ്ങളും മാതൃകകളും നൽകുന്നു
Answer:
കത്തെഴുത്ത്

കത്തെഴുത്ത് ഒരു കലയാണ്, വ്യക്തിത്വ പ്രകാശനമാണ്, വ്യക്തിബന്ധങ്ങളുടെ അരക്കിട്ടുറപ്പിക്കലാണ്, ആശയവിനിമയവും സംവേദനവുമാണ്. ചരിത്രം സൃഷ്ടിച്ച കത്തുകളുണ്ട്. സാഹിത്യമൂല്യത്തിന്റെ കാര്യ ത്തിൽ ഏതു ക്ലാസിക് കൃതിയോടും കിടപിടിക്കുന്ന കത്തുകൾ എഴുതപ്പെട്ടിട്ടുണ്ട്. ഇന്ത്യയിലെ സർവാദരണീയനായിരുന്ന പ്രധാനമന്ത്രി ജവഹർലാൽ നെഹ്റു തന്റെ മകൾ ഇന്ദിരാഗാന്ധിക്ക് ജയിലിൽ കിടന്നുകൊണ്ട് എഴുതിയ കത്തുകൾ, “ഒരച്ഛൻ മകൾക്കയച്ച കത്തുകൾ’ എന്ന പേരിൽ മികച്ച സാഹിത്യ സൃഷ്ടിയായി ഗണിക്കപ്പെട്ടിട്ടുണ്ട്. അനൗപചാരിക (Informal) അഥവാ വ്യക്തിപരമായ (Personal) എന്ന വിഭാഗത്തിൽ സാങ്കേതികമായി ഉൾപ്പെടുത്താവുന്നവയാണ് ആ കത്തുകൾ, പക്ഷെ, അതിന്റെ ഉള്ളടക്കം കൊണ്ട്, വ്യക്തിപരമായ ഊഷ്മളബന്ധങ്ങളുടെ പരിധി കടന്ന് സാർവകാലികമായ പ്രശ്നങ്ങളെ അപഗ്രഥിക്കുന്നുണ്ട്. അത്തരം കത്തുകൾ വിരളമായേ പിറവിയെടുക്കാറുള്ളൂ. അതെന്തായാലും കത്തെഴുത്തിന്റെ പ്രാധാന്യവും പ്രസക്തിയും ഊന്നിപ്പറയാൻ ഈ തുടക്കം ഉപകരിച്ചെന്നു കരുതട്ടെ..

കത്തുകൾ പലതരത്തിലുണ്ട് അനൗപചാരികം (informal) വ്യക്തിപരമായ (personal) ഔപചാരികം ( formal) ഔദ്യോഗികം (official) വ്യാപാരപരം (bussiness letters) അർദ്ധ ഔദ്യോഗിക കത്തുകൾ (Demi official letters) തുടങ്ങി കത്തുകളുടെ വൈവിധ്യങ്ങൾ ഏറെയാണ്

നമുക്ക് രണ്ടു തരത്തിലുള്ള കത്തുകൾ ആണ് പഠിക്കാനുള്ളത് ഔപചാരിക കത്തുകളും അനൗപചാരിക
കത്തുകളും

1. അനൗപചാരിക കത്തുകൾ (informal letters)

  • കത്തെഴുതുന്നയാളിന്റെ വിലാസം പേജിന്റെ വലതുവശത്ത് മുകൾ ഭാഗത്തായി കൊടുക്കാവുന്നതാണ് അഡ്രസ്സിന് താഴെ തീയതിയും ചേർക്കാം.
  • ഇടതു വശത്ത് മുകളിൽ എഴുത്തുകാരനെ അഭിസംബോധന ചെയ്തുകൊണ്ട് തുടങ്ങാം.

അഭിസംബോധന ചെയ്യുമ്പോൾ:
(i) അടുത്തറിയുന്ന ബന്ധു, കൂട്ടുകാരൻ, സഹോദരസ്ഥാനിയർ തുടങ്ങിയ ആർക്കെങ്കിലും ആണ് കത്ത് എഴുതുന്നതെങ്കിൽ അവരുടെ പേര് / വിളിപ്പേരോ ചേർത്ത് അഭിസംബോധന ചെയ്യാം).
ഉദാ : രാജുവിന്…, എന്റെ അമ്മുവിന്.., പ്രിയപ്പെട്ട മോഹൻ …
ഇങ്ങനെയൊക്കെ തുടങ്ങാം.

(ii) മാതാപിതാക്കൾ, കുടുംബത്തിലെ മുതിർന്ന ബന്ധുക്കൾ തുടങ്ങിയവരാണെങ്കിൽ അഭിസംബോധന ബഹുമാനാർത്ഥം വേണം.
ഉദാ: പ്രിയപ്പെട്ട അമ്മയ്ക്ക് / അച്ഛന് …
പ്രിയപ്പെട്ട കുട്ടേട്ടന്… എന്റെ പ്രിയപ്പെട്ട അച്ഛമ്മയ്ക്ക്… ഇങ്ങനെ അഭിസംബോധനയിലും ബഹുമാനാർത്ഥം ഏട്ടൻ അമ്മ അമ്മാവൻ എന്നൊക്കെ ചേർക്കാം…

(iii) കത്തിന്റെ വിഷയം വ്യക്തിപരമാകുന്നത് കൊണ്ട് തന്നെ അതിന് ഒരു തുടക്കവും നല്ല അവസാനവും വേണമെന്നല്ലാതെ പ്രത്യേകിച്ച് നിബന്ധനകൾ ഒന്നുമില്ല.

(iv) കത്ത് അവസാനിപ്പിക്കുന്നതിന് ഉപയോഗിക്കുന്ന വാക്കുകളിലും വ്യക്തിപരമായ കത്തിന്റെ അടുപ്പം
തോന്നിച്ചിരിക്കണം.
ഉദാ : എന്ന് കുട്ടേട്ടന്റെ സ്വന്തം കുഞ്ഞുമോൾ
എന്ന് അമ്മയുടെ സ്വന്തം ചക്കി.
എന്ന് സസ്നേഹം ചിത്ര.
എന്ന് സ്നേഹത്തോടെ അമ്മമ്മയുടെ പാറുക്കുട്ടി
ഇങ്ങനെയുള്ള അവസാനിപ്പിക്കലിൽ വായിക്കുന്ന ആളിൽ അടുപ്പവും നേരിൽ സംസാരിക്കുന്ന അനുഭവവും ലഭിക്കും

(v) വ്യക്തിപരമായ കത്തുകളിൽ ‘നീ വിഷമിക്കാതിരിക്ക്’ ‘ഞാൻ നന്നായി ചെയ്തു കൊള്ളാം’ ‘ഞാൻ തീർച്ചയായും വരും’ ‘നീ എനിക്ക് എഴുതാൻ മറക്കരുത്’ തുടങ്ങി സംഭാഷണപരമായ വാഗ്ദാനങ്ങൾ ആശ്വാസവചനങ്ങൾ എന്നിവയൊക്കെ ചേർക്കാം

ഭഗീരഥപ്രയത്നം Notes Question Answer Class 8 Adisthana Padavali Chapter 9

മാതൃക 1.

തിരുവനന്തപുരം
8/12/25

പ്രിയപ്പെട്ട അച്ഛനും അമ്മയ്ക്കും..

ഇന്നലെയാണ് ഹോസ്റ്റൽ വാർഡൻ അച്ഛന്റെ കത്ത് തന്നത്. ഞാൻ സുഖമായിരിക്കുന്നു. ഉണ്ണി മോളോട് നന്നായി പഠിക്കാൻ പറയണം. അടുത്തയാഴ്ചയാണ് പരീക്ഷ തുടങ്ങുന്നത്. പരീക്ഷ ഫീസ് ചെലാൻ അടച്ചുവെന്നും അറിയാൻ കഴിഞ്ഞു. കഴിഞ്ഞ പരീക്ഷയിലെയും മികച്ച മാർക്ക് നേടാൻ ഞാൻ ശ്രമിക്കുന്നുണ്ട്. അച്ഛാ… ഇത്തവണ തീർച്ചയായും ഷോർട്ട് ലിസ്റ്റിൽ ഞാൻ ഉണ്ടായിരിക്കും.

പരീക്ഷ കഴിഞ്ഞ് നാലുദിവസത്തെ ലീവ് ഉണ്ട്. ട്രെയിൻ ടിക്കറ്റ് ലഭിച്ച ഉടനെ ഞാൻ വരാം ഇവിടെ മറ്റു വിശേഷങ്ങൾ ഒന്നും ഇല്ല. ഞാൻ അന്വേഷിച്ചതായി എല്ലാവരോടും പറയണേ…

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മാതൃക 2.

ബാംഗ്ലൂർ
15 – 9 – 25

പ്രിയപ്പെട്ട മഹി..
നിനക്ക് സുഖം തന്നെയല്ലേ … ബാംഗ്ലൂർ ആയതുകൊണ്ട് തന്നെ കണ്ടിട്ട് ഏറെയായി. നീ അയച്ച ചേച്ചിയുടെ കല്യാണ ക്ഷണക്കത്ത് കിട്ടി. സന്തോഷം. ഈ അവധിക്ക് നാട്ടിൽ വരുന്നുണ്ട്. അച്ഛന് ലീവ് എത്ര ദിവസത്തേക്ക് അനുവദിക്കുമെന്ന് ഇപ്പോൾ പറയാൻ ആവില്ല . പരമാവധി കല്യാണത്തിന് വരാൻ ശ്രമിക്കാം. 14 വയസ്സിൽ താഴെയുള്ളവരുടെ സംസ്ഥാനതല ക്രിക്കറ്റ് ടീമിൽ കഴിഞ്ഞതവണ നീ സെലക്ട് ആയതല്ലേ ?
നിനക്ക് ഇത്തവണ നാഷണൽ ടീമിലേക്ക് സെലക്ഷൻ കിട്ടിയോ..? കിട്ടട്ടെ എന്ന് ഞാൻ പ്രാർത്ഥിക്കാം നന്നായി പ്രാക്ടീസ് ചെയ്യു…
വിജയാശംസകൾ…
നാട്ടിലെ കൂട്ടുകാരെ കാണുമ്പോൾ എന്റെ അന്വേഷണം പറയണേ …

എന്ന് സ്നേഹം
നിന്റെ സ്വന്തം സച്ചു

To
മഹേഷ്
മാവേലിക്കര
കേരളം.

ഔപചാരിക കത്തുകൾ (formal letter)
ഒരു വ്യക്തി ഉന്നത സ്ഥാനത്തുള്ള വ്യക്തിക്കോ, ഉദ്യോഗസ്ഥന്മാർക്കോ രണ്ട് സ്ഥാപനങ്ങൾ തമ്മിലോ കാര്യം മാത്രം പ്രസക്തവും മര്യാദയുടെ ഭാഷയിലുമുള്ള നിയന്ത്രിതമായ വാക്കുകളിലൂടെയുള്ള കത്തുകളാണ് ഔപചാരിക കത്തുകൾ.

  1. കത്തെഴുതുന്നയാളിന്റെ പൂർണ്ണമായ പേരും വിലാസവും ഇടതുഭാഗത്ത് മുകളിലായി കൊടുക്കണം. (ഇത് ചില ഔദ്യോഗിക കത്തുകളിൽ വലതുഭാഗത്ത് കൊടുക്കാവുന്നതും കാണുന്നു)
  2. ഇടതുഭാഗത്ത് കത്തെഴുതുന്ന ആളുടെ വിലാസത്തിന് താഴെ രണ്ട് വരിയുടെ താഴെയായി ലഭിക്കേണ്ട ആളുടെ പേര് സ്ഥാപനത്തിന്റെ പേര് വിലാസം എന്നിവ എഴുതുക
  3. ഉയർന്ന ഉദ്യോഗസ്ഥർക്കാണ് കത്തെഴുതുന്നത് എങ്കിൽ അവരുടെ സ്ഥാനവും രേഖപ്പെടുത്തണം
  4. ഔപചാരിക കത്തുകളിൽ കത്ത് ലഭിക്കുന്നയാൾ ബഹുമാന്യ സ്ഥാനത്തിരിക്കുന്നതിനാൽ തന്നെ അവരെ ബഹുമാനപ്പെട്ട …. ബഹുമാന്യ എന്നിങ്ങനെ അഭിസംബോധന ചെയ്യേണ്ടതാണ്.
  5. അഭിസംബോധനയ്ക്ക് തൊട്ടു താഴെ വിഷയം എന്താണെന്ന് കാണിക്കുന്നത് നല്ലതായിരിക്കും.
    ഉദാ : 1. കുടിവെള്ളം മുടങ്ങിയത് സംബന്ധിച്ച്
    2. പ്രളയ ദുരിതബാധിതരുടെ പുനരധിവാസം സംബന്ധിച്ച്
  6. ഇങ്ങനെ വിഷയം അവതരിപ്പിച്ച ശേഷം
    കത്തിന്റെ പൂർണ്ണവിവരം വളരെ ചുരുങ്ങിയ വാക്കുകൾ കൊണ്ട് അവതരിപ്പിക്കാം
  7. അനുബന്ധമായി അധിക വിവരങ്ങൾക്കോ മറ്റോ എന്തെങ്കിലും രേഖകൾ സമർപ്പിക്കുന്നു എങ്കിൽ സമർപ്പിച്ച രേഖകളുടെയോ ചിത്രങ്ങളുടെയോ വിവരങ്ങൾ നൽകാം
  8. കത്ത് അവസാനിപ്പിക്കുന്നത് നന്ദിയോടെ വിശ്വസ്തതയോടെ എന്നീ ബഹുമാന രീതികളിൽ ആവണം അതിനു താഴെ പേരും ഒപ്പും വയ്ക്കണം
  9. കത്തെഴുതിയ തീയതി പേജിന്റെ മുകളിൽ വലത്തേ അറ്റത്തോ താഴെ ഇടത്തെ അറ്റത്ത് വയ്ക്കാവുന്നതാണ്

മാതൃക 1. (അപേക്ഷ)

12/10/25

മഹേഷ് പ്രഭു
അമൃത നിവാസ്
എടത്തറ, പാലക്കാട്
കേരളം

മാക്സിമം പബ്ലിക്കേഷൻസ്
കിൻഫ്ര പാർക്ക് (po)
കൊരട്ടി

സർ….

ഞാൻ എട്ടാം ക്ലാസ് വിദ്യാർത്ഥിയാണ്. പുതിയ പാഠ്യപദ്ധതി അനുസരിച്ച് തയ്യാറാക്കിയ ഗൈഡുകൾ തപാൽ മാർഗം ലഭിക്കുന്നതിന് അപേക്ഷിക്കുന്നു. കേരളപാഠാവലിയുടെയും അടിസ്ഥാനപാഠാവലിയുടെ ഓരോ പുസ്തകങ്ങളാണ് ആവശ്യമായിട്ടുള്ളത്. പുസ്തകം ലഭിക്കുന്ന മുറയ്ക്ക് പണം അടയ്ക്കുവാനുള്ള സംവിധാനം ചെയ്തു തരുവാൻ അപേക്ഷിക്കുന്നു.

എന്ന് വിശ്വസ്തതയോടെ
മഹേഷ് പ്രഭു

മാതൃക 2. (നിവേദനം)

അർജുൻ
സോപാനം
പാലക്കാട്

ഡിസ്ട്രിക് ട്രാൻസ്പോർട്ട് ഓഫീസർ
K.S.R.T.C

സാർ…
വിഷയം: കെ എസ് ആർ ടി സി യുടെ പരാധീനതകൾ താങ്കളുടെ ശ്രദ്ധയിൽ കൊണ്ടുവന്ന് നടപടി സ്വീകരിക്കുന്നതിന്.

ഞങ്ങളുടെ വിദ്യാലയം (വിദ്യാലയത്തിന്റെ പേര്) മെയിൻ റോഡിന് ചേർന്നാണ്. വിദ്യാലയത്തിന്റെ മുന്നിലുള്ള വിശാലമായ പാത ബസ് സർവീസിനു അനുയോജ്യമാണ് വിദ്യാലയത്തിൽ നിന്ന് കുറച്ചു മാറിയാണ് സ്റ്റോപ്പ് ഉള്ളത്. അതുകൊണ്ടുതന്നെ വിദ്യാലയത്തിന്റെ മുന്നിലൂടെ പോകുന്ന കെഎസ്ആർടിസി ബസ്സുകൾ നിർത്താറില്ല. കുട്ടികൾ റോഡ് മുറിച്ചു കിടക്കുമ്പോഴും സ്കൂൾ പരിസരപ്രദേശം എന്ന വേഗത പരിധികൾ കെഎസ്ആർടിസി ബസുകൾ പാലിക്കുന്നില്ല. സ്കൂളിനു മുന്നിൽ സ്പീഡ് ബ്രേക്കർ പോലുള്ള സംവിധാനങ്ങൾ ഇല്ലാത്തതും ഒരു കാരണമാണ്. അപകടകരമായ സാഹചര്യത്തിൽ കെഎസ്ആർടിസി സർവീസുകൾ ശ്രദ്ധയിൽപ്പെട്ടതുകൊണ്ടാണ് ഇങ്ങനെ ഒരു കത്ത് എഴുതുന്നത്. അനുയോജ്യമായ നടപടികൾ സ്വീകരിക്കുമെന്ന് പ്രതീക്ഷയോടെ വിദ്യാർത്ഥികൾ

പാലക്കാട്
8 – 7 – 25

എന്ന്
വിശ്വസ്ഥത യോടെ
1. (പേര്, ഒപ്പ്)

പത്രവാർത്ത തയ്യാറാക്കാം
ഒരു നല്ല പത്രവാർത്ത (news report) തയ്യാറാക്കുമ്പോൾ ശ്രദ്ധിക്കേണ്ട പ്രധാനപ്പെട്ട കാര്യങ്ങൾ താഴെ ചേർക്കുന്നു. ഇവ പാലിച്ചാൽ വാർത്ത കൃത്യവും ആകർഷകവുമാവും:

  1. നല്ല തലക്കെട്ട് ഉണ്ടാവണം
    തലക്കെട്ട് (heading) ചുരുക്കത്തിൽ ആകർഷകമായും വാർത്തയുടെ ആത്മാവിനും അനുസരിച്ചും എഴുതണം. വാർത്തയുടെ വിശദാംശങ്ങൾ വായിക്കാൻ ആകർഷണം തോന്നും വിധം ആയിരിക്കണം
  2. ആര്, എവിടെ, എപ്പോൾ, എന്ത്, എന്തിനാണ്, എങ്ങനെ എന്നിങ്ങനെയുള്ള 6 ചോദ്യങ്ങൾക്കുള്ള ഉത്തരം വാർത്തയിൽ ഉൾപ്പെടണം:
  3. ഏറ്റവും ആദ്യം സംഭവം നടന്ന സ്ഥലം കൊടുക്കണം എവിടെയാണ് സംഭവിച്ചത്? (Where?)
  4. ആമുഖം: പ്രധാന വിവരങ്ങൾ (ആർക്കാണ് സംഭവിച്ചത്, എന്താണ് സംഭവിച്ചത്) ആര് (Who?)
  5. മുഖ്യവിവരണം: സംഭവത്തെക്കുറിച്ചുള്ള വിശദീകരണം (വ്യക്തികൾ, ഇടങ്ങൾ, പ്രാധാന്യം) എന്താണ് സംഭവിച്ചത്? (What? എപ്പോഴാണ്? (When?) എന്തിനാണ് സംഭവിച്ചത്? (Why?) എങ്ങനെയാണ് സംഭവിച്ചത്? (How?)
  6. അവസാനം: പ്രതികരണങ്ങൾ, പിന്നാമ്പുറങ്ങൾ, ഭാവിപരിസ്ഥിതികൾ
  7. വാർത്തയുടെ ഭാഷ ലളിതവും സുതാര്യവും ആയിരിക്കണം.
  8. പേരുകൾ, തിയതികൾ, സമയം, സ്ഥലം എന്നിവ കൃത്യമായി നൽകണം
  9. സംഭവത്തിൽ പങ്കാളികളായവരുടെ കൃത്യമായ അഭിപ്രായങ്ങൾ ചേർക്കാവുന്നതാണ്. വിശ്വസ്തമായ ഉറവിടങ്ങൾക്കു മാത്രമേ ആശ്രയിക്കാവൂ. പരമാവധി കൃത്യത ഉറപ്പാക്കണം.

“ശുഭാംശുവിന് ഭൂമിയിലേക്ക് സ്വാഗതം”
കാലിഫോർണിയ : ശാന്തസമുദ്രത്തിൽ സുരക്ഷിതമായി പതിച്ച ഡ്രാഗൺ പേടകത്തിൽനിന്ന് പുറത്തിറങ്ങി ഗ്രൂപ്പ് ക്യാപ്റ്റൻ ശുഭാംശു ശുക്ല. 18 ദിവസം നീണ്ട ആക്സിയം4 ദൗത്യം വിജയകരമായി പൂർത്തിയാക്കിയാണ് ശുഭാംഭു ഭൂമിയിൽ 15.7.25 നു ഇന്ത്യൻ സമയം 3.01 നു തിരിച്ചെത്തിയത്. ശുഭാംശു പേടകത്തിൽനിന്ന് പുറത്തിറങ്ങുന്നതിന്റെയും ആഴ്ചകൾക്കുശേഷം ആദ്യമായി ഗുരുത്വാകർഷണം അനുഭവിക്കുമ്പോൾ മറ്റുള്ളവർ സഹായിക്കുന്നതിന്റെയും വീഡിയോ ദൃശ്യങ്ങളടക്കം പുറത്തുവന്നിട്ടുണ്ട്. സ്പേസ് എക്സിന്റെ ഡ്രാഗൺ ബഹിരാകാശ പേടകം ഇന്ത്യൻ സമയം ഏകദേശം 3:01 നാണ് സാൻ ഡീഗോയ്ക്ക് സമീപം ശാന്തസമുദ്രത്തിൽ സുരക്ഷിതമായി സാഷ് ഡൗൺ ചെയ്തത്. സ്ഥലത്ത് തയ്യാറാക്കി നിർത്തിയിരിക്കുന്ന ബോട്ടുകൾ പേടകം വീണ്ടെടുത്തു. ശുഭാംശു അടക്കമുള്ളവർക്ക് ഇനി ഭൂമിയുടെ ഗുരുത്വാകർഷണവുമായി പൊരുത്തപ്പെടുന്നതിനു വേണ്ടി ഏഴുദിവസം പുനരധിവാസമുണ്ടാകും.

(ഈ വാർത്ത വായിച്ചു നോക്കൂ എവിടെ സംഭവിച്ചു? എപ്പോൾ സംഭവിച്ചു? ആര്? എങ്ങനെ? എന്തിന്? ഇനിയെന്താണ് നടക്കുന്നത്? തുടങ്ങിയ എല്ലാ ചോദ്യങ്ങൾക്കുമുള്ള ഉത്തരം ലഭിച്ചില്ലേ..? ഇതേപോലെതന്നെ ഒരു സംഭവം കൂട്ടുകാർ വാർത്തയാക്കുമ്പോൾ ഇത്തരം കാര്യങ്ങളെല്ലാം ഉൾപ്പെട്ടിട്ടുണ്ടോ എന്നും ഭാഷ ലളിതവും സുതാര്യവുമാണ് എന്നും ശ്രദ്ധിച്ചാൽ മതിയാവും).

ഡയറി എഴുതാം
ഒരു ഡയറി എഴുതുമ്പോൾ ശ്രദ്ധിക്കേണ്ട പ്രധാന കാര്യങ്ങൾ താഴെക്കൊടുത്തിരിക്കുന്നു. ഡയറി ഒരു വ്യക്തിപരമായ എഴുത്തായതിനാൽ, അതിൽ സത്യസന്ധത, സ്വതന്ത്രത, മാനസികാവസ്ഥ എന്നിവ സ്വന്തം താല്പര്യങ്ങൾക്ക് അനുസരിച്ച് ചേർക്കാം. എന്നാൽ, നല്ല ഒരു ഡയറി കുറിപ്പിന് ചില നിർബന്ധമായ ഘടകങ്ങളും ശ്രദ്ധിക്കേണ്ടതുമുണ്ട്.

  1. തിയതി, ദിവസം, സമയം ചേർക്കുക
  2. ഡയറി ഒരാളുടെ ആത്മസംഭാഷണമാണ്, അതുകൊണ്ട് അതിൽ സത്യം കാണണം കൃത്രിമത്വം ഒഴിവാക്കണം മറ്റുള്ളവർ വായിക്കും എന്ന ഭയമില്ലാതെ തുറന്നെഴുതണം (അതായിരിക്കും ശരിയായ ‘ഡയറി’)
  3. വ്യക്തിപരമായ അനുഭവങ്ങളും വികാരങ്ങളും തുറന്നും നിർഭയമായി എഴുതാം
    ഉദാ: ഇന്ന് മനസ്സിന് വലിയ സന്തോഷമാണ് തോന്നുന്നത്…
    ഒരു വിങ്ങലൂടെയാണ് ഞാൻ ഇത് എഴുതുന്നത്…
    ഇങ്ങനെയൊക്കെ നമ്മുടെ അന്നത്തെ സുപ്രധാന മനോഭാവത്തെ കേന്ദ്രീകരിച്ച് ഡയറി എഴുതാം
  4. തനിയെ സംസാരിക്കുന്ന രീതിയിൽ എഴുതുക
    ഉദാ : “ഞാൻ”, “എനിക്ക്”, “എന്റെ” എന്ന രീതിയിൽ –
  5. വിഷയങ്ങൾക്ക് ക്രമമുണ്ടാകണം
    ഉദാ : ആ ദിവസത്തെ പ്രധാന സംഭവങ്ങൾ → അതിനെച്ചൊരിച്ചുള്ള മനോഭാവങ്ങൾ → ആകെയുള്ള മനസിലാക്കൽ/ബോധം/പാഠം
  6. അനുഭവങ്ങൾ മാത്രമല്ല, ചിന്തകളും ഉൾപ്പെടുത്തുക
  7. “ഇനിമുതൽ ഞാൻ…” പോലുള്ള ആലോചനകൾക്ക് ഇടം നൽകുക
  8. ഡയറിയെ ഒരു ആത്മമിത്രമായി കാണുക
    എല്ലായ്പ്പോഴും മനസ്സിലുള്ളത് തുറന്ന് പറയാൻ ഒരു മറുപടി പ്രതീക്ഷിക്കാതെ എഴുതാം പിറകിൽ തിരികെ വായിക്കുമ്പോൾ നിങ്ങൾക്ക് തന്നെ ബോധം വരുന്നതായിരിക്കണം

ഭഗീരഥപ്രയത്നം Notes Question Answer Class 8 Adisthana Padavali Chapter 9

മാതൃക

3 – 4 – 25
തിങ്കൾ

ഇന്ന് എന്റെ ജീവിതത്തിലെ ഞാൻ ഇതുവരെ കണ്ടിട്ടില്ലാത്ത ചിന്തിച്ചിട്ടില്ലാത്ത ഒരു അധ്യായം ആയിരുന്നു കടന്നുപോയത്.

ഉച്ചയ്ക്ക് ഊണ് കഴിക്കാൻ ചോറ്റുപാത്രം എടുക്കാൻ തിരിഞ്ഞപ്പോഴാണ് ബാഗിൽ പാത്രമില്ല. ഞാൻ ചുറ്റിലും നോക്കി എവിടെയും കാണുന്നില്ല. കൂട്ടുകാരെല്ലാവരും ഭക്ഷണം കഴിച്ചു തുടങ്ങി.. ഞാൻ വരാന്തയിലും മുറ്റത്തും പോയി നോക്കി ബസ് ഇറങ്ങി വരുമ്പോൾ വഴിയിൽ എങ്ങാനും വീണു കാണുമോ…? ഇല്ല എവിടെയും ഇല്ല. വിശപ്പ് അതിന്റെ നിലവിളി തുടങ്ങിയിരുന്നു. എനിക്ക് കരച്ചിൽ വന്നു. തൽക്കാലത്തേക്ക് ഒരു ഗ്ലാസ് വെള്ളം കുടിക്കാനായി ഞാൻ വരാന്തയുടെ അറ്റത്തേക്ക് നടന്നു . അപ്പോഴാണ് എന്റെ പൂമ്പാറ്റ ചിത്രം ഒട്ടിച്ച് ചോറ്റു പാത്രവുമായി സഞ്ജു നിൽക്കുന്നു. അവൻ ആ ചോറ്റുപാത്രം എന്റെ നേർക്ക് നീട്ടിയിട്ട് സോറി പറഞ്ഞു തിരിച്ചു പോയി…

അവൻ എന്തിനാണ് എന്നോട് സോറി പറഞ്ഞത്? പാത്രം തുറന്ന് കഴിക്കാനിരുന്നപ്പോൾ എന്റെ എന്റെ ഉള്ളിൽ കത്തി നിന്ന വിശപ്പ് മരവിച്ചു പോയിരുന്നു. പാത്രം അടച്ച് ഞാൻ വരാന്തയിലേക്ക് ചെന്നു. സഞ്ജു വെള്ളം കുടിച്ചു കൊണ്ട് നിൽക്കുകയായിരുന്നു. അതെ അവനു വിശന്നിട്ടാണ്… വേറെ ഒന്നും ചോദിക്കാതെ പാത്രത്തിൽ നിന്ന് രണ്ട് ചപ്പാത്തിയും കറിയും അടപ്പിലേക്ക് പകർന്നു ഞാൻ അവനു നേരെ നീട്ടി. അവൻ ഒന്നും മിണ്ടാതെ അത് വാങ്ങിച്ചു കഴിച്ചു. കൂട്ടുകാരിൽ ചിലരിൽ നിന്ന് ഞാൻ അവന്റെ സ്ഥിതിഗതികൾ മനസ്സിലാക്കി. അമ്മ പറഞ്ഞിട്ടുണ്ട് നാളെ മുതൽ എനിക്ക് രണ്ട് പത്രത്തിൽ ഭക്ഷണം നൽകാമെന്ന്…

(ഈ ഡയറിക്കുറിപ്പ് വായിച്ചു നോക്കൂ അന്നത്തെ അനുഭവം പങ്കുവെക്കുന്നതിനോടൊപ്പം മനസ്സിൽ തോന്നിയ വികാരങ്ങളും സംഭാഷണങ്ങളും തുറന്ന് എഴുതിയിട്ടില്ലേ… ലളിതവും സുന്ദരവുമായ ഭാഷയല്ലേ ഉപയോഗിച്ചതത്? ഇതേ ഇപ്രകാരം കൂട്ടുകാരുടെ ഓർമ്മകൾ എഴുതിത്തുടങ്ങൂ…)

(നോട്ടീസ് തയ്യാറാക്കുന്നതിന്റെയും ലഘുലേഖ തയ്യാറാക്കുന്നതിന്റെയും മാതൃകകൾ പഠന പ്രവർത്തനങ്ങൾ നൽകിയത് നോക്കുമല്ലോ…

ഏതൊരു പഠന പ്രവർത്തനമായാലും എന്ത്? എപ്പോൾ? എങ്ങനെ? എവിടെ? ആര്? തുടങ്ങിയ ചോദ്യങ്ങൾക്ക് നിങ്ങൾ തയ്യാറാക്കിയ മാതൃകയിൽ ഉത്തരം ഉണ്ടോ എന്ന് വിലയിരുത്തുക)

ഭഗീരഥപ്രയത്നം Summary in Malayalam Class 8

Students can use Class 8 Malayalam Adisthana Padavali Notes Pdf and ഭഗീരഥപ്രയത്നം Bhagiratha Prayatnam Summary in Malayalam to grasp the key points of a lengthy text.

Class 8 Malayalam Bhagiratha Prayatnam Summary

Bhagiratha Prayatnam Summary in Malayalam

ഭഗീരഥപ്രയത്നം Summary in Malayalam

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ഡോ. എം. വല്യത്താൻ
ഭഗീരഥപ്രയത്നം Summary in Malayalam Class 8 1
ഒരു ഇന്ത്യൻ കാർഡിയാക് സർജനാണ് മാർത്ത് വർമ്മ ശങ്കരൻ വലിയത്താൻ അഥവാ എം. എസ്. വല്യത്താൻ (ജനനം: 24 മെയ് 1934 – മരണം: 18 ജൂലൈ 2024) ഇന്ത്യൻ നാഷണൽ സയൻസ് അക്കാദമിയുടെ മുൻ പ്രസിഡന്റും ഇന്ത്യാ ഗവൺമെന്റിന്റെ ദേശീയ ഗവേഷണ പ്രൊഫസറുമായിരുന്നു. പിൽക്കാലത്ത് ആയുർവേദത്തെ കുറിച്ച് മനസ്സിലാക്കുകയും അതിന്റെ പ്രയോക്താവായിത്തീരുകയും ചെയ്തു ആയുർവേദത്തിലെ മൂലഗ്രന്ഥങ്ങളായ ചരകസംഹിത സുശ്രുത സംഹിത വാഗ്ഭട സംഹിത എന്നിവയെ അധികരിച്ച് ഗ്രന്ഥരചന നടത്തുകയും ചെയ്തു. ഇന്ത്യയിലെ ആരോഗ്യ സാങ്കേതികവിദ്യയ്ക്ക് നൽകിയ സംഭാവനകൾക്ക് 2005 ൽ പത്മവിഭൂഷൻ അവാർഡ് ലഭിച്ചു. 1999 ൽ ഫ്രഞ്ച് സർക്കാർ നൽകിയ ബഹുമതിയായ ഓർഡ ഡെസ് പാംസ് അക്കാഡെമിക്സിൽ അദ്ദേഹത്തെ ഷെവലിയറാക്കി. അന്താരാഷ്ട്ര മെഡിക്കൽ വിദ്യാഭ്യാസത്തിനുള്ള സംഭാവനകൾക്ക് 2009 ൽ ജോൺസ് ഹോപ്കിൻസ് യൂണിവേഴ്സിറ്റി മെഡിക്കൽ സ്കൂളിൽ നിന്ന് ഡോ. സാമുവൽ പി. ആർ ഇന്റർനാഷണൽ അവാർഡ് ലഭിച്ചു.

വി. ഡി. സെൽവരാജ്
പ്രശസ്ത മലയാള മാസികയായ ‘കലാകൗമുദി’യുടെ ഡെപ്യൂട്ടി എഡിറ്ററായി സേവനമനുഷ്ഠിക്കുന്ന സെൽവരാജിന് പത്രപ്രവർത്തനത്തിൽ പതിറ്റാണ്ടുകളുടെ പരിചയമുണ്ട്. അടൂർ ഗോപാലകൃഷ്ണനും എം.എ. ബേബിയും തമ്മിലുള്ള സംഭാഷണങ്ങളുടെ സമാഹാരമായ ‘ഗബ്രിയേൽ ഗാർസിയ മാർക്വേസ് മുതൽ കേളുചരൺ മഹാപത്ര വരെ: അടൂർ ഗോപാലകൃഷ്ണൻ, എം.എ. ബേബി’ എന്ന പുസ്തകവും അദ്ദേഹം പുറത്തിറക്കിയിട്ടുണ്ട്
ഡോക്ടർ എം എസ് വല്യത്താനുമായി നടത്തിയ അഭിമുഖത്തിന്റെ പശ്ചാത്തലത്തിലുള്ള ലേഖനമാണ് “മയൂരി ശിഖ ജീവിതം അനുഭവം അറിവ്.”

ഭഗീരഥപ്രയത്നം Summary in Malayalam Class 8

പാഠസംഗ്രഹം

ജീവിതത്തിൽ വിജയം നേടാൻ ഏകാഗ്രതയും കഠിനപ്രയത്നവുമാണ് അവശ്യ മെന്നു. ഡോ.എം.എസ്. വല്യത്താനും ഡോ. വി.ഡി. ശെൽവരാജും ചേർന്ന അഭിമുഖത്തെ അധികരിച്ച് എഴുതിയ “ഭഗീരഥപ്രയത്നം’ എന്ന ലേഖനം ഈ സത്യത്തെ ആധികാരികമായി വ്യക്തമാക്കുന്നു. വിജയത്തിന് പിന്നിലുള്ള പരീക്ഷണങ്ങളും പരാജയങ്ങളും നിറഞ്ഞ ദീർഘമായ ശാസ്ത്രീയപ്രയാണം ആണ് ഇവിടെയുള്ള പ്രമേയം.
ഭഗീരഥപ്രയത്നം Summary in Malayalam Class 8 2
1982-ൽ ശ്രീചിത്ര തിരുനാൾ ഇൻസ്റ്റിറ്റ്യൂട്ടിൽ ആരംഭിച്ച ഹൃദയവാൽവ് വികസനശ്രമം, ഭാരതത്തിലെ നൂതന വൈദ്യശാസ്ത്ര ചരിത്രത്തിൽ മഹത്തായ ഘടകമായി മാറി. പൂർവകാല കഥാ പുരാണങ്ങളിലെ ഭഗീരഥൻ ഗംഗയെ ഭൂമിയിലേക്കിറക്കാൻ നടത്തിയ ധീരമായ ശ്രമത്തെപ്പോലെ, നിരന്തരമായ പരിശ്രമം ഇവിടെയും നടക്കുകയായിരുന്നു. ഏഴുവർഷം നീണ്ട ഈ ഗവേഷണത്തിൽ ആദ്യത്തെ മൂന്ന് മോഡലുകൾ പരാജയപ്പെട്ടെങ്കിലും ടീമിന്റെ ആത്മവിശ്വാസം തളർന്നില്ല. ആടുകളിൽ നടത്തിയ പരീക്ഷണങ്ങൾ വിജയിച്ചപ്പോൾ മാത്രമേ സാങ്കേതികവിദ്യയുടെ വിജയഭാവം ഉറപ്പിക്കാനായുള്ളൂ.
ഭഗീരഥപ്രയത്നം Summary in Malayalam Class 8 3
സാങ്കേതികപരമായി വികസിപ്പിച്ച വാൽവിന്റെ ഘടകങ്ങൾ ഒട്ടും സാധാരണമായിരുന്നില്ല. ഫ്രയിം നിർമ്മിച്ചത് ക്രോമിയം കോബാൾട്ട് അലോയിൽ നിന്നാണ് – (വിമാനനിർമാണത്തിൽ ഉപയോഗിക്കുന്നത്). ഡിസ്കിന് ഉപയോഗിച്ചത് ‘അൾട്രാ ഹൈ പോളി എതിലിൻ’ എന്ന പ്രത്യേക പ്ലാസ്റ്റിക്. പ്ലാസ്റ്റിക് ഫാബ്രിക് നിർമിച്ചത് കോയമ്പത്തൂരിലെ ഒരു ടെക്സ്റ്റൈൽ സ്ഥാപനമായിരുന്നു. ഇത് ഈ ഗവേഷണത്തിന് ദക്ഷിണേന്ത്യയുടെ വിവിധ മേഖലകളിൽ നിന്നുള്ള സാങ്കേതിക പിന്തുണ ലഭിച്ചിരുന്നതിന്റെ തെളിവാണ്.

പൊതുസമൂഹവും മാധ്യമങ്ങളും വാൽവ് നിർമ്മാണ പ്രയത്നം തുടങ്ങിയ ഘട്ടങ്ങളിൽ ഈ സംരംഭത്തെ കുറിച്ച് അവഹേളന പൂർണ്ണമായ അഭിപ്രായങ്ങൾ പ്രകടിപ്പിച്ചു. അതുകൊണ്ടു തന്നെ ശാസ്ത്രത്തിന്റെ കൃത്യതയിൽ വിശ്വസിച്ച ഗവേഷകർക്ക് ഈ എതിർ പ്രതികരണങ്ങൾ വലിയ ചലനം ഉണ്ടാക്കിയെങ്കിലും, അതെല്ലാം പ്രചോദനമായി സ്വീകരിച്ചു മുന്നോട്ടുപോയതായിരുന്നു അവരുടെ കരുത്ത്. ഒടുവിൽ ടി.ടി.കെ. കമ്പനിയുടെ സഹകരണത്തോടെ വാൽവ് വാണിജ്യാടിസ്ഥാനത്തിൽ വിപണിയിലെത്തി. ഇന്ന് ലക്ഷത്തിൽ അധികം ആളുകൾ ഈ വാൽവിന്റെ സഹായത്തോടെ ജീവിക്കുന്നു എന്നത് അതിന്റെ വിജയത്തിന്റെ തെളിവാണ്.

ഭാരതീയ ശാസ്ത്ര പുരോഗതിക്ക് വഴിയൊരുക്കിയവരുടെ ജീവിതം പരാജയങ്ങളുടെയും വീഴ്ചകളുടെയും കഥകളും ആണ്. അതിനാൽ വിജയങ്ങൾ മാത്രം നോക്കാതെ, അതിന് പിന്നിലെ നീണ്ട യാത്രകളും തിരിച്ചടികളും മനസ്സിലാക്കണം. ഭർത്തൃഹരിയുടെ ശ്ലോകം ഈ ആശയം ഉയർത്തിപ്പിടിക്കുന്നു – നീചർ ശ്രമം പോലും തുടങ്ങില്ല, മധ്യമർ വഴിയിൽ വിട്ടു വെക്കും, എന്നാൽ ഉത്തമർ വിജയത്തിലേക്ക് ആഗ്രഹിക്കുന്നവരെപ്പോലെ ഒറ്റമനസോടെ പിന്നോട്ടില്ലാതെ മുന്നോട്ട് പോവുമെന്നാണ്.

ഭഗീരഥപ്രയത്നം നമ്മെ പഠിപ്പിക്കുന്നത്, മനസ്സിനുള്ളിൽ വെറും ആശയമായി’ തുടങ്ങിയതെന്തും അടിയന്തിരമായി യാഥാർഥ്യത്തിലാകണമെങ്കിൽ, അതിന് പരിശ്രമം, സഹനം, പ്രതീക്ഷ, ആത്മവിശ്വാസം എന്നിവ അനിവാര്യമാണ് എന്നതാണ്. വിജയത്തിന് വഴിയൊരുക്കുന്ന സംവേദനാത്മകമായ ഈ കൃതി ശാസ്ത്രജ്ഞരുടെ ജീവിതത്തിന്റെയും മനസ്സിന്റെയും ആത്മാവാണ്.

ഭഗീരഥപ്രയത്നം Summary in Malayalam Class 8

പുതിയ പദങ്ങൾ

ഭഗീരഥപ്രയത്നം = ഏറെ അദ്ധ്വാനം ചെയ്യുന്ന ദീർഘകാല ശ്രമം (ഭഗീരഥൻ ഗംഗയെ ഭൂമിയിൽ കൊണ്ടുവരാൻ നടത്തിയ വലിയ പരിശ്രമം സൂചിപ്പിക്കുന്നു)
സഫലീ = ഫലപ്രദമായത് / വിജയിച്ചത്
വിഘ്നം = തടസ്സം
ഉന്നതർ = ഉയർന്ന നിലവാരം
നീച്ചർ = താഴ്ന്ന നിലവാരം
വിദ്വേഷം = അപകീർത്തിപ്പെടുത്തൽ
നീതിശതകം = ഭർത്തൃഹരിയുടെ പാഠരചന.

തോട്ടക്കാരി Summary in Malayalam Class 8

Students can use Class 8 Malayalam Adisthana Padavali Notes Pdf and തോട്ടക്കാരി Thottakkari Summary in Malayalam to grasp the key points of a lengthy text.

Class 8 Malayalam Thottakkari Summary

Thottakkari Summary in Malayalam

തോട്ടക്കാരി Summary in Malayalam

എഴുത്തുകാരനെ പരിചയപ്പെടാം
തോട്ടക്കാരി Summary in Malayalam Class 8 1
പി. ഭാസ്കരൻ : മലയാളത്തിലെ ഒരു പ്രശസ്ത കവിയും, ഗാനരചയിതാവു മായിരുന്നു പി.ഭാസ്കരൻ. ഗാനരചയിതാവ്, ചലച്ചിത്രസംവിധായകൻ, ചലച്ചിത്രനടൻ, ആകാശവാണി പ്രൊഡ്യൂസർ, സ്വാതന്ത്ര്യ സമര സേനാനി, ആദ്യകാല കമ്യൂണിസ്റ്റ് പ്രവർത്തകൻ, പത്രപ്രവർത്തകൻ എന്നിങ്ങനെ വിവിധ നിലകളിലും അദ്ദേഹം പ്രവർത്തിച്ചിരുന്നു.

തന്റെ ഇരുപതാമത്തെ വയസിൽത്തന്നെ ആദ്യ കവിതാസമാഹാരം പുറത്തിറക്കിയ അദ്ദേഹം, എക്കാലത്തും കാല്പനികത ലളിതമായി ചിത്രീകരിക്കാനാണ് ശ്രമിച്ചിട്ടുള്ളതെന്നാണ് നിരൂപകരുടെ അഭിപ്രായം. മലയാളചലച്ചിത്രഗാനശാഖയിൽ സംസ്കൃതാതിപ്രസരവും, മറ്റുഭാഷകളിലെ ഗാനങ്ങളുടെ തത്സമങ്ങളും വിളങ്ങിനിന്നിരുന്ന കാലത്ത്, ഒരു ലളിത ഗാന ശൈലി ഉണ്ടാക്കിയത് ഭാസ്കരൻ മാസ്റ്റർ ആണെന്ന് ഏവരും സമ്മതിക്കും.

“മലയാള ഭാഷയുടെ പിതാവ് തുഞ്ചത്തെഴുത്തച്ഛനാണെങ്കിൽ മലയാള ഗാനങ്ങളുടെ പിതാവ് പി. ഭാസ്കരൻ ആണ്.” എന്നാണ് യൂസഫലി കേച്ചേരി പറഞ്ഞിട്ടുള്ളത്. കാൽപ്പനികതക്ക് ജനകീയത നൽകിയ അദ്ദേഹം, നിരാശാന്തമായ ആധുനിക സാഹിത്യത്തിൽ വിശ്വസിച്ചിരുന്നില്ല.

ഓർക്കുക വല്ലപ്പോഴും, ഒറ്റക്കമ്പിയുള്ള തമ്പുരു, വയലാർ ഗർജ്ജിക്കുന്നു, ഒസ്യത്ത്, പാടുന്ന മൺതരികൾ, ഓടക്കുഴലും ലാത്തിയും തുടങ്ങിയവയാണ് പ്രധാന കൃതികൾ. ഒറ്റക്കമ്പിയുള്ള തമ്പുരു എന്ന കൃതിക്ക് 1981ൽ ഓടക്കുഴൽ പുരസ്കാരവും, 82ൽ കേരള സാഹിത്യ അക്കാദമി പുരസ്കാരവും ലഭിച്ചു. കേരള സാഹിത്യ അക്കാദമിയുടെ ഫെലോഷിപ്പും ലഭിച്ചിട്ടുണ്ട്. 2000 ൽ വള്ളത്തോൾ അവാർഡും ലഭിച്ചു.

തോട്ടക്കാരി Summary in Malayalam Class 8

പാഠസംഗ്രഹം

പി. ഭാസ്കരന്റെ “തോട്ടക്കാരി’ എന്ന കവിതയിൽ അവന്റെ വീട്ടിലെ പൂന്തോട്ട ത്തിന്റെയും അതിലുണ്ടായ മാറിനില്ക്കലുകളുടെയും പശ്ചാത്തലത്തിൽ ഒരാളുടെയും ഭാര്യയുടെയും തമ്മിലുള്ള ആത്മബന്ധം ആവിഷ്കരിക്കുന്നു. ജീവിതത്തിലെ ചെറിയ ചെറിയ സംഭവങ്ങൾക്കിടയിലൂടെയാണ് സ്നേഹത്തിന്റെ ആഴം തെളിയുന്നത്. താറുമാറായ തോട്ടത്തെ നോക്കി അതിലെ വാടിപ്പോയ പച്ചപ്പിൽ നിന്നുള്ള ദുഃഖം പങ്കുവയ്ക്കുന്ന ഭാര്യയുടെ മുഖം കാണുമ്പോൾ, കവിയുടെ ഉള്ളിൽ വല്ലാതൊരു കുറ്റബോധവും സ്നേഹഭാവവും പടർന്ന് നിൽക്കുന്നു.
തോട്ടക്കാരി Summary in Malayalam Class 8 2

ഇവിടെയുള്ള ‘തോട്ടം’ ഒരു ഉപമാസ്വരൂപമായി കാണാം – കുടുംബജീവിതത്തിന്റെ ശുഭതക്കും, സ്ത്രീയുടെ വാത്സല്യത്തിനും, നിലനില്പിനുമുള്ള സൂചനയായി. അവളുടെ കണ്ണീരിലേക്കും തണലായ ചിരിയിലേക്കും കടന്നുപോകുന്ന കവിയുടെ മനസ്സ് സ്ത്രീയുടെ സ്നേഹത്തെ വർഷമേഘം പോലെ വിശേഷിപ്പിക്കുന്നു. ഈ ആത്മനിമഗ്നമായ കാവ്യം സ്നേഹത്തെയും വീട്ടിലെയും സൗഹൃദപരവുമായ ബന്ധത്തെയും വരച്ചുകാട്ടുന്നു.

പുതിയ പദങ്ങൾ

മറുനാട് = വിദേശീ
വിഷണ്ണനായ് = വിഷാദം നിറഞ്ഞ മനസ്സാടെ; നിരാശയോടെ
നിശാഗന്ധി = രാത്രി സുഗന്ധം വിടുന്ന പൂക്കൾ
നിലം പൊത്തി = പൂർണ്ണമായും നശിച്ചു മണ്ണോട് ചേർന്നതുപോലെ
വർഷമേഘം = മഴമേഘം (സ്നേഹത്തിന്റെ പ്രതീകം)
ചിന്നിക്കാണായ് = പൊട്ടി പുറത്തു കാണുക