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Class 10 Chemistry Chapter 17 Reaction Kinetics Test 3
Class 10 chemistry chapter 17 reaction kinetics test mcq
Prepare for your matric Chemistry examination with the Class 10 Chemistry Chapter 17 Reaction Kinetics Class Test 3, part of the Punjab Board 2027 Model Papers series. This chapter-wise Chemistry test helps students revise important concepts from Chapter 17: Reaction Kinetics and strengthen their exam preparation. Practice Chemistry questions, assess your understanding, and improve your performance through regular revision and self-assessment. These Class 10 Chemistry Model Papers 2027 are useful for students preparing for Punjab Board examinations under the latest syllabus. Visit 786Times.com for more Class 10 Chemistry chapter-wise tests, matric model papers, and educational resources.
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Chapter Wise Class Test
T-3
Chapter-17
Reaction Kinetics
1.
According to collision theory, a reaction occurs when:
(a) molecules are heated
(b) molecules collide
(c) molecules change color
(d) pressure is reduced
Answer: (b) molecules collide
2.
Activation energy is:
(a) Maximum energy of molecules
(b) Minimum energy required to start a reaction
(c) Average energy of molecules
(d) Energy of products
Answer: (b) Minimum energy required to start a reaction
3.
The energy barrier in a reaction is known as:
(a) Kinetic energy
(b) Activation energy
(c) Potential energy
(d) Heat of reaction
Answer: (b) Activation energy
4.
When magnesium burns in air in an open crucible:
(a) Mass decreases
(b) Mass remains the same
(c) Mass increases
(d) Mass disappears
Answer: (c) Mass increases
5.
During a reaction, the concentration of reactants:
(a) Increases
(b) Decreases
(c) Remains constant
(d) First decreases then increases
Answer: (b) Decreases
6.
Why does the temperature of surroundings increase in an exothermic reaction?
(a) Heat is absorbed from surroundings
(b) Heat is released to surroundings
(c) Heat is destroyed
(d) No energy change occurs
Answer: (b) Heat is released to surroundings
7.
What happens to the container when ammonium nitrate dissolves in water?
(a) It becomes hot
(b) It breaks
(c) It becomes cool
(d) No change occurs
Answer: (c) It becomes cool
8.
According to collision theory, the rate of a chemical reaction depends on:
(a) Number of particles only
(b) Number of successful collisions per second
(c) Temperature only
(d) Pressure only
Answer: (b) Number of successful collisions per second
(P.T.O)
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Chapter Wise Class Test
T-3
Chapter-17
Reaction Kinetics
2. Write short answers to any six (6) questions.[6 × 2 = 12]
(i)
What is an effective collision?
A collision between reactant particles that have at least the activation energy and the correct orientation, so that products are formed.
(ii)
Explain the effect of temperature on reaction rate.
Raising the temperature increases the kinetic energy and speed of particles, so more collisions occur and more of them have energy ≥ Ea; the rate increases (about double for a 10°C rise).
(iii)
Why does a reaction sometimes appear to change mass?
In an open vessel a gas may escape (mass appears to decrease) or be taken in from air (mass appears to increase), e.g. Mg + O2 → MgO.
(iv)
Why is mass conserved in a closed container?
No substance can enter or escape, and atoms are only rearranged, not created or destroyed, so total mass stays the same.
(v)
What is an exothermic reaction? Give one example.
A reaction that releases heat to the surroundings (ΔH is negative). Example: burning of methane, CH4 + 2O2 → CO2 + 2H2O + heat.
(vi)
How does temperature affect the rate of a chemical reaction?
Increasing temperature increases the rate; decreasing temperature lowers it, because the number of effective collisions per second changes.
(vii)
What does collision theory explain about chemical reactions?
It explains that a reaction occurs only when particles collide with sufficient energy and proper orientation, and that the rate depends on the number of successful collisions per second.
(viii)
What happens to the reactant particles after collision?
If the collision is effective, bonds in the reactants break and new bonds form to give products; otherwise the particles simply bounce apart unchanged.
(ix)
Define activation Energy.
The minimum energy that colliding particles must possess to start a chemical reaction (symbol Ea).
Note: Attempt any one question.[5 × 1 = 5]
3.
Describe the main points of the collision theory of reaction rate.
- Reaction occurs only when reactant particles collide.
- Only collisions with energy ≥ activation energy (Ea) are effective.
- Particles must collide with the correct orientation.
- Rate ∝ number of effective collisions per second.
- Higher temperature, concentration, pressure (gases) or surface area increases collisions and so the rate.
4.
Explain change in mass during a chemical reaction.
- Total mass is conserved in a closed system (law of conservation of mass).
- Open vessel, gas produced and escapes: mass appears to decrease, e.g. CaCO3 → CaO + CO2↑.
- Open vessel, gas taken from air: mass appears to increase, e.g. 2Mg + O2 → 2MgO.
- In a closed container, the mass of reactants always equals the mass of products.
