Kerala Syllabus Class 10 Chemistry Model Question Paper Set 3

Practicing Chemistry Question Paper Class 10 Kerala Syllabus Set 3 English Medium helps identify strengths and weaknesses in a subject.

Chemistry Class 10 Kerala Syllabus Model Question Paper Set 3

Time: 1 ½ Hours
Total Score: 40

Instruction:

1. First fifteen minutes are cool off time. Read the questions carefully during this time:
2. Write the answers according to the instructions.
3. Consider the score while writing the answers.
4. Answer only one question for questions having choice.

Answer all the questions from 1 to 4. Each question carries 1 score. (1 × 4 = 4)

Question 1.
Which substance is deposited at the cathode when aqueous Sodium Chloride is electrolysed?
[Oxygen, Chlorine, Sodium, Hydrogen]

Set 1	Set 2
(a) H2C2O4	(i) Acid salts
(b) NaOH	(ii) Tribasic acid
(c) H3PO4	(iii) Alkali
(d) NH4C1	(iv) Dibasic acid

Answer:
Hydrogen

Question 2.
Match the following.
Choose the correct answer from the options given below.
A. (a) – (iv), (b) – (iii), (c) – (ii), (d) – (i)
B. (a) – (i), (b) – (iii), (c) – (ii), (d) – (iv)
C. (a) – (iii), (b) – (iv), (c) – (ii), (d) – (i)
D. (a) – (ii), (b) – (iii), (c) – (iv), (d) – (i)
Answer:
A. (a) – (iv), (b) – (iii), (c) – (ii), (d) – (i)

Question 3.
Statement 1: Roasting refers to heating the concentrated ore at a temperature below the melting point in the presence of air.
Statement 2: Calcination refers to heating the concentrated ore in limited quantities or absence of air at a temperature below the melting point. Which of the following options is true, regarding these statements?
A. Statements 1 and 2 are correct.
B. Statement 1 is correct, but Statement 2 is not correct.
C. Statement 1 is not correct, but Statement 2 is correct.
D. Statements 1 and 2 are not correct.
Answer:
A. Statements 1 and 2 are correct.

Question 4.
To which category the compound CH₃ – COO – CH₃ belongs to?
a) Carboxylic acid
b) Ethene
c) alcohol
d) Ester
Answer:
d) Ester

Two questions from 5 to 11 have a choice. Each question carries 2 scores. (7 × 2 = 14)

Question 5.
Given Mass: 45 grams of water (H₂O), Molecular Mass of Water: 18 u
a) Calculate the number of moles of water molecules.
b) Calculate the number of molecules in the given mass.
Answer:
a) Number of Moles = \(\frac{45}{18}\) = 2.5moles
b) Number of Molecules = 2.5 × 6.022 × 1023
= 1.51 × 10²⁴ molecules

Question 6.
A. Which subshell is represented by each pair of the quantum number values given below?
a) n = 1, l = 0
b) n = 2, l = 1
Answer:
a) 1s
b) 2p

OR
B. Find the oxidation state of s-block elements in the following compounds.
a) Na₂O
b) KBr
Answer:
a) Sodium – +1
b) Potassium – +1

Question 7.
A student dissolves ammonium chloride (NH₄C₁) in water and finds the solution is acidic. Explain this observation by answering the following questions.
a) Identify the acid and base that react to form ammonium chloride (NH₄C₁).
b) Which is stronger, the acid or the base?
Answer:
a) The acid is Hydrochloric acid (HC1) and the base
is Ammonium hydroxide (NH₄OH).
b) The acid (hydrochloric acid) is stronger.

Question 8.
Complete the table.

Metal	Method of refining	Reason for selecting the method
Lead	(a)	Low melting point
Cadmium	Distillation	(b)

Answer:
a) Liquation
b) Low boiling point

Question 9.
A. The structure of two organic compounds is given below:
(i) CH₃ – CH₂ – CH₂ – CH₂ – OH
(ii) CH₃ – CH₂ – O – CH₂ – CH₃
a) Write the molecular formula of these compounds.
b) Write the structural formula of a position isomer of compound I
Answer:
a) C₂H₁₀
b) Butan – 2 – ol

OR
B. a) Write the structural formulae and IUPAC names of any two metamers of the compound
CH₃ – CH₂ – CH₂ – O – CH₂ – CH₂ – CH₃

b) Write the molecular formula of the given compound.
Answer:

b) C₆H₁₄O

Question 10.
A student draws the arrangement of a galvanic cell as shown below. Find out if there is any mistake? If so, draw the correct picture of the galvanic cell.

Answer:
Each metal should be placed in its own salt solution; that is, the Zn rod should be dipped in ZnS04, and the Cu rod should be dipped in CuS04.If the arrangement is correct, electron flow is from Zinc to copper.

Question 11.
a) Which among the following is a condensation polymer?
(Polyvinyl chloride, nylon 66, Teflon)
b) What are the monomers of nylon 66?
Answer:
a) Nylon 66
b) Adipic acid, Hexamethylenediamine.

Two questions from 12 to 17 have a choice. Each question carries 3 scores. (6 × 3 = 18)

Question 12.
The volume of 2 mol of hydrogen gas at 1 atm pressure and 273 K is 44.8 L.
a) Name the scientist who established the relationship between the volume and pressure of a gas through experiment.
b) What will be the new pressure if the volume of hydrogen gas is changed to 22.4 L?
c) Suggest a method to increase the volume of this gas without changing the pressure and mass.
Answer:
a) Robert Boyle
b) P₁V₁ = P₂V₂
P₁ = 1 atm
V₁ = 44.8L
V₂ = 22.4L
p₂ = p₁ V₁ /V₂
p₂ = \(frac{1 \times 44.8}{22.4}\) = 2 atm

c) Increase the temperature

Question 13.
A. The following are two facts related to the manufacture of an industrially important metal.
• The ore is treated with a hot NaOH solution.
• Electricity is used as the reducing agent to extract the metal.
(i) These facts are related to the production of which metal?
(ii) What is the reason for using electricity as the reducing agent?
(iii) Which substance is used as the electrolyte here?
Answer:
(i) Aluminium
(ii) Aluminium is a highly reactive and electropositive metal.
(iii) Molten cryolite (Na₃AlF₆)

OR
B. Corrosion is a process by which iron is converted into its oxide. This is an oxidation reaction.
(i) What is oxidation?
(ii) Complete the following chemical equation.
…. Fe + ….. Oz → …Fe₂O₃
(iii) Suggest two methods for preventing the corrosion of iron.
Answer:
(i) The process involving loss of electrons in a chemical reaction is called oxidation.

(ii) 4Fe + 3O₂ → 2Fe₂O₃

(iii)
• Painting or coating
• Galvanization

Question 14.
Analyse the equation and answer the following questions.

a) What is the name of this chemical reaction?
b) What is the name of the ester formed?
c) Write any two uses of esters.
Answer:
a) Esterification
b) Methyl ethanoate
c) Used to make artificial perfumes Used-to make juices.

Question 15.
Write the structural formula of the compounds given below.
a) Propan-l-ol
b) Propanal
c) Propanone
Answer:
a) CH₃CH₂CH₂OH
b) CH₃-CH₂-CHO
c) CH₃-CO-CH;

Question 16
(A)
a) Draw a diagram of the setup for electroplating gold onto a copper bangle and label its parts
b) What are the advantages of electroplating?
c) A picture of the arrangement of copper plating on an iron bangle is given below. What are the mistakes in this?

Answer:
a)

b) It enhances the beauty of metal Prevents corrosion

c) Copper should be connected to the positive terminal of the battery.
The iron bangle should be connected to the negative terminal of the battery.
Copper sulfate solution should be used as the electrolyte.

B. Analyse the pictur of an experiment.

a) What is the reason for the decrease in the green colour of the FeS04 solution?
b) The equation for this reaction is given below. Complete it.
Zn + FeSO₄  ____ + ZnSO₄
c) If Pb is used instead of Zn, no reaction takes place. From this, what inference regarding the reactivity of lead can be obtained?
Answer:
a) Zn displaces iron from the FeS0₄ solution.
b) Zn + FeS0₄ → Fe + ZnS0₄
c) Pb is less reactive than Zn.

Question 17.
Which of the following is’not correct in the subshell electron configuration?
a) 1s² 2s² 2p⁷
b) 1s² 2s² 2p²
c) 1s² 2s² 2p⁶3s¹
d) 1s²2s²⁶3s²3p⁶3d²4¹
e) 1s²2s²⁶3s²3p⁶3d²4²
Answer:
The incorrect subshell electron configuration is
a) ls²2s²2p⁷
c) ls²2s²2p⁵3s¹
d) ls²2s²2p⁶3s²3p⁶3d²4s¹

Question 18 has a choice. It carries 4. scores.

a) How many hydrogen molecules are required to convert CH = CH (ethyne) into C₂H₆ (ethane)?
b) Write the chemical equation of the reaction.
c) To which category does this chemical reaction belong?
d) Complete the chemical equation,
CH ≡ CH + HCl → A
Answer:
a) 2 Flydrogen molecules (4 Hydrogen atoms)
b) CH = CH + H₂ → CH₂ = CH₂ + H₂ → CH₃ – CH₃
Or (C₂H₆)
c) Addition reaction
d) CH = CH + HC1 → CH₂ = CHC1

OR
B. a) Identify A, B, C and D in the given chemical reactions.

b) What is wash?
c) How is rectified spirit obtained from the wash?
d) What is the purpose of denaturing rectified spirit?
Answer:
a) A – Invertase,
B – Fructose (C₆H₁₂O₆),
C – Zymase,
D – Carbon dioxide (2CO₂)

b) 8-10% ethanol obtained by the conversion of glucose and fructose by the action of the enzyme zymase is known as ‘wash’.

c) When wash is subjected to fractional distillation, 95.6% of ethanol is obtained. This is known as rectified spirit.

d) Ethanol is an organic compound used in the manufacture of various other organic compounds.

In such situations, toxic substances like methanol/ pyridine/rubber distillate, etc., are added to ethanol in order to prevent its misuse as a beverage. Ethanol thus obtained is called denatured spirit.