Kerala Syllabus Class 9 Chemistry Model Question Paper Set 5 English Medium

Teachers recommend solving Kerala Syllabus 9th Standard Chemistry Question Papers Set 5 to improve time management during exams.

Kerala Syllabus Std 9 Chemistry Model Question Paper Set 5 English Medium

Score :40
Time: 1 1⁄2 hrs.

Instructions

• First 15 minutes is given as cool off time. This time is to be spent for reading and understanding the questions.
• Answer the questions according to the directions.
• Score and time to be considered while answering.

I. Answer any four questions from 1 – 5. Each carries 1 score. (4 × 1 = 4)

Question 1.
Who proposed the law of conservation of mass?
Answer:
Antoine Lavoisier

Question 2.
Which element has the highest electronegativity?
Answer:
Fluorine

Question 3.
Identify the ions in the following compounds.
a) CaSO₄
b) Mg(OH)₂
Answer:
a) Ca²⁺ and \(\mathrm{SO}_4{ }^{2-}\)
b) Mg²⁺ and OH^–

Question 4.
The valency of the two elements is given below.
Al – 3O – 2
The chemical formula of aluminium oxide is ________
(AlO, Al₂O₃, AlO₂, A₁O₂)
Answer:
Al₂O₃

Question 5.
Find the relationship and fill it suitably
Sodium : Metal
Germanium : ________
Answer:
Metalloid

II. Answer any four questions from 6 – 10. Each carries 2 scores. (4 × 2 = 8)

Question 6.
There are 11 electrons and 12 neutrons in an atom.
a) Find out the atomic number and mass number.
b) Write the electron configuration of the element.
Answer:
Atomic number = Number of Protons = 11
Mass number = Number of protons + Number of neutrons = 11 + 12 = 23
Electro configuration = 2,8,1

Question 7.
a) Write the electron configuration of \({ }_{10}^{20} \mathrm{Ne}\) and find its group number.
b) Does the element generally take part in chemical reactions? Why?
Answer:
a) \({ }_{10}^{20} \mathrm{Ne}\) – 2,8
b) This element generally does not take part in chemical reactions. This element has stable octet (8 electron) configuration in its outer most shell. So it is chemically inert.

Question 8.
The atomic numbers of certain elements are given below.
N = 5, O= 8, CI =17
Identify the nature of covalent bonds in the molecules given below
(i) N₂
(ii) O₂
(iii) Cl₂
Answer:
N₂ – triple bond
O₂ – double bond
Cl₂ – single bond

Question 9.
What are the characteristics of transition elements?
Answer:

• Transition elements show similarity in chemical properties in groups as well as in periods.
• They are metals.
• They generally form coloured compounds.
• They show variable valency.

Question 10.
a) What are redox reactions?
b) What are oxidation and reduction?
Answer:
a) Reduction and oxidation take place simultaneously. So together they are called redox reactions.
b) Oxidation is the process of losing electrons or increasing oxidation number.
Reduction is the process of gaining of electrons or decreasing oxidation number.

III. Answer any four questions from 11 to 15. Each carries 3 scores. (4 × 3 = 12)

Question 11.
The electron configuration of certain elements is given in the table.
(Symbols are not real).

Element	Electron configuration
X	2,8,7
Y	2,8,8
Z	2,8,1

a) Which element has the biggest atom?
b) Name the family to which the element ‘Y’ belongs.
c) Which among these has stable electronic configuration?
Answer:
a) Z
b) Noble gases
c) Y

Question 12.
The mass number of an atom is 31. There are 15 positively charged particles in its nucleus.
a) Write the electron configuration of this atom.
b) How many neutrons are there in this atom?
Answer:
No: of protons (positively charged particle) = No: of electrons = 15
Electron configuration = 2, 8, 5

b) Mass number A = 31
Atomic number Z = 15
No: of neutrons = A – Z = 31 – 15 = 16

Question 13.
What are the observations of the gold foil experiment?
Answer:

• Most of the alpha particles passed through the gold foil undeflected.
• Some of the alpha particles deflected by a small angle from the straight line, when they hit the gold foil.
• A very few alpha particles deflected by 180°.

Question 14.
a) Which of the following chemical equations are balanced?
H₂ + O₂ → H₂O
CO₂ + C → 2CO
N₂ + H₂ → 2NH₃
b) Balance the unbalanced chemical equations.
Answer:
a) CO₂ + C → 2CO
b) 2H₂ + O₂ → 2H₂O
N₂ + 3H₂ → 2NH₃

Question 15.
There are 4 electrons in the M shell of an element.
a) Write the electron configuration of the element.
b) What is its atomic number?
c) Find out the period and group of the element in the periodic table.
Answer:
a) 2, 8, 4
b) 14
c) Period -3, group – 14

IV. Answer any four questions from 16-20. Each carries 4 scores. (4 × 4 = 16)

Question 16.
An incomplete form of the periodic table is given below.
(Symbols are not real)

a) Which element has the largest atoms?
b) Which are transition elements?
c) Write the electron configuration of Y.
d) Which element has the biggest size of atom?
Answer:
a) S
b) T, U
c) 2,8
d) Y

Question 17.
a) Find out the oxidation number of ‘S’ in the following compounds.
(Oxidation number H = +1 O = -2)
i) H₂SO₄
ii) SO₂
b) Analyse the following chemical equation and find out the elements that undergone oxidation, reduction, oxidising agent and reducing agent.
S + O₂ → SO₂
Answer:
a) i) (1 × 2) + S + (- 2 × 4) = 0
⁺2 + S + ⁺8 = 0
S + ^–6 = 0
S = 6

ii) S + ( -2 × 2) = 0
S + ^–4 = 0
S = 4

b) Oxidation – S
Reduction -O
Oxidising agent – O
Reducing agent – S

Question 18.
Certain cations and anions are given in the table.

Cations	Anions
Na+	\(\mathrm{SO}_4^{2-}\)
Ca2+	\(\mathrm{CO}_3{ }^{2-}\)
Al3+	\(\mathrm{OH}^{-}\)
\(\mathrm{NH}_4{ }^{+}\)	\(\mathrm{Cl}^{-}\)

Write the chemical formula of the following compounds.
a) Sodium carbonate
b) Calcium sulphate
c) Aluminium chloride
d) Ammonium hydroxide
Answer:
a) Na₂CO₃
b) CaSO₄
c) AlCl₃
d) NH₄OH

Question 19.
a) What is the neutralisation reaction?
b) Write the equation of a neutralisation reaction.
c) Find out the acid and base needed to form the salt Potassium sulphate.
Answer:
a) When an acid and alkali react together a salt with neither acidic nor alkaline nature and water is formed. Such reactions are called neutralisation reactions.
b) NaOH + HCI → NaCl + H₂O
c) Acid:- H₂SO₄ : Base:-KOH

Question 20.
The electron dot diagram of magnesium oxide is given below.

a) Which atom accepts electrons?
b) Write the equation showing the formation of Mg²⁺ ions.
c) Name the cation present in it.
d) Write the electronic configuration of the Mg²⁺
Answer:
a) Oxygen atom
b) Mg → Mg²⁺ + 2e^–
c) Magnesium
d) Electron configuration of Mg²⁺ = 2,8