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Class 10 Chemistry Chapter 17 Reaction Kinetics Test 4
Grade 10 Chemistry chapter 17 Reaction Kinetics
Prepare for the Class 10 Chemistry Chapter 17 Reaction Kinetics Class Test 4 with the Punjab Board 2027 Model Papers, available at 786Times.com. This chapter-wise Chemistry test helps students revise important concepts from Chapter 17: Reaction Kinetics and strengthen their preparation for the Class 10 Matric examinations. Practice Chemistry questions, assess your understanding, and improve your exam performance with these Class 10 Chemistry Model Papers 2027. Students preparing for Punjab Board examinations can use this test for revision, self-assessment, and additional practice according to their prescribed syllabus. Visit 786Times.com for more Class 10 Chemistry chapter-wise tests, important questions, MCQs, and Punjab Board 2027 Model Papers.
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Chapter Wise Class Test
T-4
Chapter-17
Reaction Kinetics
1.
Why do reactions occur faster when reactants are in the same phase?
(a) Because particles are smaller
(b) Because particles collide more easily
(c) Because temperature increases
(d) Because pressure decreases
Answer: (b) Because particles collide more easily
2.
Combustion of coal occurs faster in pure oxygen than in air because:
(a) Oxygen is heavier than air
(b) Pure oxygen has higher concentration of oxygen molecules
(c) Coal burns without oxygen
(d) Air contains nitrogen only
Answer: (b) Pure oxygen has higher concentration of oxygen molecules
3.
In many reaction by increasing 10oC of temperature reaction will increase by:
(a) 2 time
(b) 3 time
(c) 4 time
(d) 10 time
Answer: (a) 2 time
4.
When Limestone and HCl react in flask which gas is evolved.
(a) H2
(b) N2
(c) CO2
(d) H2O
Answer: (c) CO2
5.
Why do fruits become sweeter during ripening?
(a) Sugars convert into starch
(b) Starches convert into sugars
(c) Proteins convert into fats
(d) Fats convert into sugars
Answer: (b) Starches convert into sugars
6.
During ripening, tissues of fruits become soft because:
(a) Water evaporates
(b) Enzymatic reactions occur
(c) Minerals increase
(d) Oxygen decreases
Answer: (b) Enzymatic reactions occur
7.
Monitoring ethene production helps farmers to:
(a) Increase fertilizer use
(b) Predict the best time for harvesting
(c) Stop plant growth
(d) Change soil type
Answer: (b) Predict the best time for harvesting
8.
Studying reaction rates helps determine the best conditions for:
(a) Harvesting
(b) Storage
(c) Transportation
(d) All of these (P.T.O)
Answer: (d) All of these
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Chapter Wise Class Test
T-4
Chapter-17
Reaction Kinetics
2. Write short answers to any six (6) questions.[6 × 2 = 12]
(i)
Why are reactions often carried out in one phase?
When all reactants are in the same phase (all gases or all in solution) their particles mix completely and collide easily, so the reaction is faster and more uniform.
(ii)
Explain why limestone reacts faster with concentrated hydrochloric acid than with dilute hydrochloric acid.
Concentrated acid has more H+ and Cl− particles per unit volume, so more collisions occur per second with limestone (CaCO3) and the rate is higher. CaCO3 + 2HCl → CaCl2 + H2O + CO2↑
(iii)
Why does increasing temperature increase reaction rate?
Particles gain kinetic energy and move faster, so they collide more often and a larger fraction have energy ≥ activation energy; effective collisions increase.
(iv)
How do enzymes work?
Enzymes are biological catalysts. The substrate fits into the enzyme’s active site (lock-and-key), the reaction proceeds with lower activation energy, and the products are released while the enzyme remains unchanged.
(v)
How kinetics can help us?
It helps us control the speed of reactions: speeding up useful ones (industry, medicines) and slowing harmful ones (rusting, food spoilage), and find the best conditions for production and storage.
(vi)
How do you increase the number of successful collisions?
By increasing temperature, concentration (or pressure for gases) and surface area, and by adding a suitable catalyst.
(vii)
How do enzymatic reactions help in fruit ripening?
Enzymes (helped by ethene gas) convert starch into sugars and break down cell walls, so the fruit becomes sweet and soft.
(viii)
What changes occur in spoiled food?
Microorganisms and enzymes break down the food: its taste, smell, colour and texture change and harmful substances may form.
(ix)
Why is it important to determine optimum conditions for food storage?
The right temperature, humidity and gas conditions slow the reactions that spoil food, so it stays fresh longer, waste is reduced and quality is kept.
Note: Attempt any one question.[5 × 1 = 5]
3.
Explain the effect of catalyst on the rate of reaction.
- A catalyst changes the rate of a reaction without being used up.
- It provides an alternative path with lower activation energy (Ea).
- More particles then have enough energy, so more collisions are effective and the rate increases.
- It does not change the products or the heat of reaction (ΔH).
- Example: Pt or Ni in the addition of H2 to ethene; enzymes in living cells.
4.
How does chemical kinetics play an important role in the food industry?
- It finds the best temperature and conditions for storing food, so spoilage is slowed (e.g. refrigeration).
- It helps control ripening of fruits by monitoring ethene so harvesting and transport are timed correctly.
- It guides preservation methods such as freezing, drying and packaging.
- It supports use of enzymes in making cheese, bread and juices.
- Result: longer shelf life, less waste and better quality food.
