Kerala Syllabus Class 9 Chemistry Model Question Paper Set 2 English Medium

Teachers recommend solving Kerala Syllabus 9th Standard Chemistry Question Papers Set 2 to improve time management during exams.

Kerala Syllabus Std 9 Chemistry Model Question Paper Set 2 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.
Planetary model of atom : Rutherford
Law of conservation of mass: …………..
Answer:
Antoine Lavoisier

Question 2.
Which one of the following does not belong to the group?
(Carbon, Nitrogen, Oxygen, Hydrogen)
Answer:
Carbon

Question 3.
Which of the noble gases does not have an octet arrangement in the outermost shell?
Answer:
Helium

Question 4.
Which elements show similarity in chemical properties in groups and periods in the periodic table?
(Noble gases, Representative elements, transition elements, Lanthanoids)
Answer:
Transition elements

Question 5.
Conducts electricity in molten state as well as in solutions. This statement is applicable to what type of compounds?
Answer:
lonic compounds

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

Question 6.
Write the names of the elements included in the first period of the periodic table.
Answer:
Hydrogen, Helium.

Question 7.
Analyse the following statements and correct them, if there is a mistake.
i) The mass of an atom mainly depends upon the mass of the electrons and neutrons present in it.
ii) Down the group in a periodic table, the size of the atom decreases.
Answer:

• The mass of an atom mainly depends on the mass of protons and neutrons present in it.
• Down the group in a periodic table, the size of the atom increases.

Question 8.
What are oxidation and reduction?
Answer:
Oxidation is the loss of electrons or increasing the oxidation number.
Reduction is the gaining of electrons or decreasing the oxidation number.

Question 9.
From the following statements
Choose those applicable to covalent compounds.

• Dissolves in organic compounds
• Dissolves in water
• High melting and boiling point.
• Found in solid, liquid and gaseous states.
• Conducts electricity.

Answer:
Dissolve in organic compounds.
Find in solid, liquid and gaseous states.

Question 10.
The valency of iron (Fe) is 3 and oxygen (O) is 2.
a) Write the chemical formula of iron oxide
b) The chemical formula of aluminium chloride is AlCl₃ Write the valencies of Al and Cl.
Answer:
a) Fe₂ – O₃
b) Al – 3 Cl – 1

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

Question 11.
a) Write the equation to find out the maximum number of electrons that can be accommodated in a shell.
b) Find out the maximum number of electrons that can be accommodated in the third shell of an atom.
Answer:
a) The maximum number of electrons that can be accommodated in any orbit is 2n² (n=orbit number).
b) Third shell, n = 3
The number of electrons that can be accommodated in third shell = 2n²
= 2 × 3² = 2 × 9 = 18.

Question 12.
The atomic number of Magnesium is 12 and Fluorine is 9.
a) Write the electron configuration of these elements.
b) Write the electron dot formula of the compound formed by these two elements.
Answer:
a) Mg = 2,8,2
F = 2,7

Question 13.
Some observations related to experiments on cathode rays are given. Write the inference based on each observation.
a) A paddle wheel placed in the path of cathode rays rotates.
b) A shadow is formed if an opaque object is placed in the path of cathode rays.
c) When an electric field is applied perpendicular to the path of cathode rays, the rays deflect towards the positive plate.
Answer:
a) The particles in the cathode rays have mass.
b) Cathode rays travel in straight lines.
c) Cathode rays have a negative charge.

Question 14.
Balance the following chemical equations.
i) Zn + HCl → ZnCl₂ + H₂
ii) Mg + O₂ → MgO
iii) SO₂ + O₂ → SO₃
Answer:
i) Zn + HCl → ZnCl₂ + H₂
Step 1: Zn + HCl → ZnCl₂+ H₂
Step 2: Zn + 2HCl → ZnCl₂+ H₂
Balanced Chemical Equation:
Zn + 2HCl → ZnCl₂+ H₂

ii) Mg + O₂ → MgO
Step 1: Mg + O₂ → MgO
Step 2: Mg + O₂ → 2MgO
Step 3: 2Mg + O₂ → 2MgO
Balanced Chemical Equation:
2Mg + O₂ → 2MgO

iii) SO₂ + O₂ → SO₃
Step 1: SO₂ + O₂ → SO₃
Step 2: 2SO₂ + O₂ → SO₃
Step 3: 2SO₂ + +O₂ → 2SO₃
Balanced Chemical Equation:
2SO₂+ O₂ → 2SO₃

Question 15.
The gaseous fuel carbon monoxide burns in oxygen to form carbon dioxide.
a) Write the balanced equation of this chemical reaction.
b) Find out the oxidising and reducing agents in this reaction.
Answer:

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

Question 16.
Write an experiment to substantiate the Law of conservation of mass.
Answer:
Take 20 mL of barium chloride solution in one beaker. Take 20 mL sodium sulphate solution in another beaker. Place both beakers on an electronic balance and record the mass. Then, pour the solution from one beaker into the other. Record the mass again. There will be no difference in mass. This is because the total mass of the reactants is equal to the total mass of the products.

Question 17.
Find out the oxidation number of ‘Cr’ in the following compounds.
(Hint: oxidation number K = +1, 0 = −2)
(i) Cr₂O₇
(ii) K₂Cr₂O₇
Answer:
i) 2Cr + (7 × -2) = 0
2 Cr + -14 = 0
2 Cr = +14
Cr = +7
The oxidation number of Cr in Cr₂O₇ is +7.

ii) (2 ×+1) + 2Cr + (7 × -2) = 0
+ 2 + 2Cr + -14 = 0
2Cr + – 12 = 0
2Cr = +12
Cr = \(\frac { +12 }{ 2 }\) = +6
Cr = +6
The oxidation number of Cr in K₂Cr₂O₂ = +6

Question 18.
The molecular formula of Carbon tetrachloride is CCl₄
[Hint: Electronegativity C = 2.55 and Cl = 3.16; Atomic number C = 6 and Cl = 17]
a) How many electrons are present in the outermost shell of carbon?
b) Which type of chemical bonding is present in CCl₄?
c) Draw the electron dot diagram of the formation of CCl₄.
Answer:
a) 4
b) Covalent bonding (single bond)
C = -2.55
Cl = 3.16
Electronegativity difference = 3.16 – 2.55 = 0.61 < 1.7
Thus, covalent bonding.

Question 19.
The mass number of an atom is 32. There are 6 electrons in the ‘M’ shell.
a) Write the electron configuration of this element.
b) What is the number of neutrons?
c) Draw the Bohr model of the atom.
Answer:
a) Mass number of the atom = 32
There are 6 electrons in the M shell which means the K and L shells are completely filled.
The number of electrons in the K shell = 2
The number of electrons in the L shell = 8
The number of electrons in the M shell = 6
So, the total number of electrons = 16
Thus, number of protons – Atomic number = 16
Number of neutrons = Mass number – Atomic number 32-16= 16
b) Electron configuration of atom = 2,8,6
c) Orbit electronic configuration of the atom

Question 20.
Certain isotopes and their uses are given in the following table. Match them suitably.

A	B
Phosphorus – 31	Determination of the age of fossils.
lodine -131	Nuclear fuel
Uranium – 235	As a tracer of materials transportation in plants.
Carbon-14	Treatment of cancer and tumour

Answer:

A	B
Phosphorus – 31	As a tracer of materials transportation in plants.
lodine -131	Treatment of cancer and tumour
Uranium – 235	Nuclear fuel
Carbon-14	Determination of the age of fossils.