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Class 10 Chemistry Chapter 17 Reaction Kinetics Test 1
Class 10 Chemistry Chapter 17 Reaction Kinetics
Prepare for your matric board examinations with the Class 10 Chemistry Chapter 17 Reaction Kinetics Class Test 1, part of the Punjab Board 2027 Model Papers. This test is designed to help students revise important concepts of Reaction Kinetics, practise examination-style questions, and strengthen their understanding of chemical reaction rates and the factors affecting them. Use this Class 10 Chemistry Chapter 17 Test 1 for revision, self-assessment, and effective preparation for the Punjab Board Class 10 Chemistry examination under the 2026–27 syllabus.
TIME: 10 MINTOTAL MARKS:30MARKS: 10
1. Collisions that actually lead to the formation of products are called:
(a) ineffective collisions(b) effective collisions
(c) neutral collisions(d) elastic collisions
Ans. (b) effective collisions
2. According to collision theory, only particles with having activation energy is:
(a) less than average(b) average
(c) equal or greater than activation(d) zero
Ans. (c) equal or greater than activation
3. Decrease in mass during the reaction of marble and HCl is due to:
(a) Escape of water(b) CO2 gas escapes
(c) Absorption of HCl(d) Formation of complex
Ans. (b) CO2 gas escapes — CaCO3 + 2HCl → CaCl2 + H2O + CO2↑
4. Reaction of quick lime (CaO) with water is an example of:
(a) Complex reaction(b) Endothermic reaction
(c) Exothermic reaction(d) No reaction occur
Ans. (c) Exothermic reaction — CaO + H2O → Ca(OH)2 + heat
5. For many reactions, the rate approximately doubles with every:
(a) 5°C rise in temperature(b) 10°C rise in temperature
(c) 20°C rise in temperature(d) 50°C rise in temperature
Ans. (b) 10°C rise in temperature
6. Reactions proceed faster when reactant are:
(a) different phases(b) the same phase(c) solid only(d) not collide
Ans. (b) the same phase
7. The volume of evolved carbon dioxide gas measure by scale:
(a) Screw guage(b) Measuring cylinder
(c) Gas syringe(d) Flask
Ans. (c) Gas syringe
8. A steeper reaction curve at the start of an experiment indicates:
(a) Slower rate of reaction(b) Faster rate of reaction
(c) No reaction(d) Constant rate
Ans. (b) Faster rate of reaction
9. In the reaction between hydrogen and chlorine gases, the rate doubles if:
(a) Pressure of hydrogen is doubled
(b) Pressure of chlorine is doubled (with hydrogen in excess)
(c) Temperature decreases(d) Both gases are diluted
Ans. (b) Pressure of chlorine is doubled (with hydrogen in excess)
10. Enzymes are:
(a) Chemical catalysts(b) Biological catalysts(c) Metals(d) Acids
Ans. (b) Biological catalysts
TIME: 22 MIN MARKS: 20
Attempt any 10 Questions.10×2=20
i.What is meant by rate of reaction?
Ans. The change in concentration of a reactant or a product per unit time is called the rate of reaction. Its unit is mol dm−3 s−1.
Rate = change in concentration / time taken
ii.How reaction take place ?
Ans. According to collision theory, a reaction takes place when reactant particles collide with proper orientation and with energy equal to or greater than the activation energy. Such effective collisions break the old bonds and form new bonds, giving the products.
iii.Which factor depends upon the effective collisions.
Ans. The rate of reaction depends upon the number of effective collisions. A collision is effective only if the particles have energy ≥ activation energy and the correct orientation.
iv.Explain in brief the sequence of energy change during a reaction.
Ans.
- The reactants first absorb energy equal to the activation energy (Ea) to break their bonds, so their energy rises to a maximum.
- At the top of the energy hill the activated complex (transition state) is formed.
- The complex breaks down and new bonds form, releasing energy, and the products are formed.
- The net difference between the energy of products and reactants is the heat of reaction (ΔH): negative for exothermic, positive for endothermic reactions.
Fig: Energy profile of an exothermic reaction
v.Give an example where mass increases during a reaction.
Ans. Burning of magnesium ribbon in air: the product MgO weighs more than the Mg because oxygen from the air combines with it. Rusting of iron is another example.
2Mg + O2 → 2MgO
vi.Why is mass conserved in a closed container?
Ans. In a closed container no gas can escape and no substance can enter, so the total mass of the reactants equals the total mass of the products (law of conservation of mass).
vii.Define exothermic reaction. Give example.
Ans. A reaction in which heat energy is released to the surroundings is called an exothermic reaction. Example:
CaO + H2O → Ca(OH)2 + heat
viii.Why does cooking food require high temperature?
Ans. At high temperature the particles gain more kinetic energy and move faster, so more of them have energy ≥ activation energy. More effective collisions occur and the food cooks quickly.
ix.Why does coal burn faster in pure oxygen than in air?
Ans. Air contains only about 21% oxygen, whereas pure oxygen is 100%. The higher concentration of O2 gives more collisions per unit time with carbon, so coal burns faster.
x.Give examples showing surface area affects reaction rate.
Ans.
- Powdered marble (CaCO3) reacts with HCl faster than marble chips.
- Small pieces of wood burn faster than a big log.
- Coal dust or flour dust can burn explosively, while lumps burn slowly.
xi.How does a catalyst increase the rate of reaction?
Ans. A catalyst provides an alternative path for the reaction with a lower activation energy. More particles then have enough energy to react, so the rate increases. The catalyst is not used up in the reaction.
xii.How do enzymes work?
Ans. Enzymes are biological catalysts (proteins). The substrate fits into the active site of the enzyme (lock and key) to form an enzyme–substrate complex. This lowers the activation energy; the products are then released and the enzyme is free to be used again.
xiii.Why is the study of reaction rates important in the food industry?
Ans. It helps to control the speed of spoilage and so decide shelf life, storage temperature (refrigeration slows reactions) and use of preservatives. It is also needed to control cooking time, fermentation (bread, curd) and ripening.
xivHow can farmers determine the best time to harvest fruits?
Ans. Ripening is a chemical process whose rate depends on temperature. By observing the rate of ripening (colour change, softness, sweetness) farmers can harvest the fruit when it is mature but not overripe, so it stays fresh during transport and storage.
