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Class 10 Chemistry Chapter 17 Reaction Kinetics Full Unit Test
Grade 10 Chemistry Chapter 17 full unit Test
Prepare for the Class 10 Chemistry Chapter 17: Reaction Kinetics Full Unit Test (Class Test 7) with the Punjab Board 2027 Model Papers, available at 786Times.com. This full unit test is designed to help students revise important concepts, assess their subject knowledge, and strengthen their preparation for the Class 10 Chemistry examination. Covering Chapter 17: Reaction Kinetics, this test provides an opportunity to practise chapter-related questions and evaluate your understanding of chemical reaction rates and the factors affecting reaction kinetics. Students can use this Class 10 Chemistry Full Unit Test for revision, self-assessment, and exam preparation according to the relevant Punjab Board syllabus. Explore more Class 10 Chemistry chapter-wise tests, Punjab Board 2027 Model Papers, important questions, and exam preparation resources at 786Times.com.
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PAPER NO.
07
CHEMISTRY
CHAPTER
WISE
WISE
Roll No.(in Figures):(in Words):
Chapter 17:Maximum Marks: 12
Reaction KineticsOBJECTIVE TYPETime Allowed : 15 Minutes
ABCD
1
2
3
4
ABCD
5
6
7
8
ABCD
9
10
11
12
NOTE:Four possible answers A, B, C and D to each question are given. The choice which you think is correct, fill that circle in front of that question with Marker or Pen ink. Cutting or filling two or more circles will result in zero mark in that question.
Q1.12
1.
The number of collisions per unit volume of the reaction mixture is called:
(A) Collision energy(B) Activation energy(C) Collision frequency(D) Collision force
Answer: (C) Collision frequency
2.
Collisions which lead to reaction are called:
(A) Effective collisions(B) Ineffective collisions(C) Inactive collisions(D) Random collisions
Answer: (A) Effective collisions
3.
The total mass during a chemical reaction always:
(A) Remains the same(B) Decreases(C) Increases(D) Doubles
Answer: (A) Remains the same
4.
If the reactants possess an energy higher than the activation energy, then the reaction will be:
(A) Slow(B) Fast(C) Not affected(D) Instantaneous
Answer: (B) Fast
5.
In which container does total mass remain same for gas-involving reactions?
(A) Open container(B) Closed container(C) Both containers(D) Round container
Answer: (B) Closed container
6.
A catalyst lowers:
(A) Concentration of reactants(B) Temperature of reaction(C) Activation energy(D) Mass of products
Answer: (C) Activation energy
7.
Which of the following explains the increase in rate of reaction in the presence of a catalyst?
(A) Catalyst provides extra energy to the reactant molecules(B) Catalyst provides an alternative pathway which lowers the activation energy.(C) Catalyst increases the collision frequency(D) Catalyst decreases the collision frequency
Answer: (B) Catalyst provides an alternative pathway which lowers the activation energy.
8.
To prevent rapid spoilage during transport, which method is used?
(A) Heating(B) Refrigeration(C) Adding acid(D) Exposing to sunlight
Answer: (B) Refrigeration
9.
Faster diffusion leads to higher drug concentration at target organ means:
(A) Less effective response(B) No response(C) More effective response(D) Harmful response
Answer: (C) More effective response
10.
Which of the following statements is correct?
(A) Collisions with energy equal to or greater than the activation energy lead to reaction.(B) Collision frequency is not related to the reaction rate(C) All collisions lead to a reaction.(D) Collisions with energy less than the activation energy lead to the reaction.
Answer: (A) Collisions with energy equal to or greater than the activation energy lead to reaction.
11.
Once absorbed by blood, drug molecules start diffusing into:
(A) Stomach only(B) Intestine only(C) Various tissues and organs(D) Blood only
Answer: (C) Various tissues and organs
12.
When a reaction proceeds ahead, how the concentrations of reactants and products change?
(A) Concentration of reactants increases and that of the products decreases.(B) Concentration of reactants decreases and that of the products increases.(C) Concentration of both reactants and products decreases.(D) Concentration of both reactants and products increases.
Answer: (B) Concentration of reactants decreases and that of the products increases.
Here is Subjective Part of Paper.
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Roll No.(in Figures):(in Words):
Chapter 17:SUBJECTIVE TYPEMaximum Marks: 48
Reaction Kinetics(PART – I)Time Allowed :1.45 Hour
Q2. Write short answers to any FIVE (5) questions:(5×2=10)
(i)
What is meant by rate of reaction?
The change in concentration of reactants or products per unit time (unit: mol dm−3 s−1).
(ii)
What are effective collisions?
Collisions between reactant particles having energy equal to or greater than the activation energy and the proper orientation, which lead to formation of products.
(iii)
How does increase in the temperature increase the rate of a reaction?
A rise in temperature gives particles more kinetic energy, so they collide more often and a larger fraction of collisions have energy ≥ Ea; the rate increases (roughly doubles for a 10°C rise).
(iv)
What happens after the high energy state is formed during a reaction?
The high-energy (activated) state is unstable; bonds of the reactants break, new bonds form, and it falls to the lower-energy state of the products.
(v)
Define activation energy.
The minimum energy that reactant particles must have to start a chemical reaction (symbol Ea).
(vi)
What happens to mass if a gas is evolved in an open container?
The gas escapes into the air, so the mass of the container contents appears to decrease.
(vii)
Why does the burning of sulphur proceed slower in air than in pure oxygen?
Air has only about 21% oxygen, so the concentration of O2 molecules is lower and fewer collisions occur with sulphur; pure oxygen has a higher concentration, so the rate is faster.
(viii)
What are exothermic reactions?
Reactions that release heat energy to the surroundings (ΔH is negative), e.g. burning of fuels.
Q3. Write short answers to any FIVE (5) questions:(5×2=10)
(i)
Why a catalyst used in a reaction is preferably taken in the powdered form?
Powder has a larger surface area, so more reactant particles touch the catalyst at once (more active sites) and the reaction is faster.
(ii)
Give an example of an endothermic reaction.
Decomposition of limestone on heating: CaCO3 → CaO + CO2 (heat is absorbed). Dissolving of ammonium nitrate in water is another example.
(iii)
Why is the rate of a reaction often very fast at the beginning of the reaction?
At the beginning the concentration of reactants is highest, so collisions per second are most frequent; the rate falls as the reactants are used up.
(iv)
How does collision theory explain the effect of temperature on rate of reaction?
Higher temperature increases the speed and energy of particles, giving more collisions per second and more collisions with energy ≥ Ea, so more effective collisions occur and the rate rises.
(v)
Magnesium does not react with air at room temperature but it reacts very fast at high temperature giving intense white light. Explain.
At room temperature the particles do not have energy equal to the activation energy, so collisions are not effective. On heating, they gain energy ≥ Ea and burn rapidly: 2Mg + O2 → 2MgO, releasing heat and intense white light.
(vi)
Give an example showing effect of concentration on rate of reaction.
Coal (or sulphur) burns faster in pure oxygen than in air because pure oxygen has a higher concentration of O2. Limestone also reacts faster with concentrated HCl than with dilute HCl.
(vii)
What happens to the reactants after they climb the energy hill during a reaction?
After reaching the top of the energy hill (activated complex) they roll down to the lower energy level and change into products.
(viii)
How does surface area affect the rate of reaction?
Larger surface area exposes more particles to collisions, so more effective collisions occur and the rate increases; smaller surface area gives a slower rate.
Q4. Write short answers to any FIVE (5) questions:(5×2=10)
(i)
How does a catalyst lower the activation energy of a reaction?
It provides an alternative pathway (reaction route) which needs less energy, so more particles can react.
(ii)
What is a catalyst?
A substance that changes the rate of a chemical reaction without being consumed in the reaction.
(iii)
Give any two features of the catalytic action of an enzyme.
- Highly specific: the active site fits only a particular substrate.
- Works at an optimum temperature and pH, and is not used up in the reaction.
(iv)
Define enzymes.
Enzymes are biological catalysts (proteins) produced by living cells that speed up biochemical reactions.
(v)
Give an example of a reaction which proceeds with the gain in mass.
Burning of magnesium in air in an open vessel: 2Mg + O2 → 2MgO; the oxygen from air combines with Mg, so the mass increases. Rusting of iron is another example.
(vi)
How would you determine the best time of fruit harvesting?
By monitoring the amount of ethene gas released by the fruit; a rise in ethene shows that ripening is starting, so harvesting is timed accordingly.
(vii)
If you desire to stop a reaction going on at 60°C, what action you will take?
Cool the reaction mixture quickly (e.g. in an ice bath) to lower the temperature, which lowers the rate; removing the catalyst or diluting the reactants also helps.
(viii)
How do drug molecules reach different parts of the body?
After absorption into the blood they are carried by circulation and then diffuse through cell membranes into various tissues and organs.
(PART – II)
Note: Attempt any TWO questions.(2 × 9 = 18)
Q5.(a)Explain the effect of surface area on the rate of a reaction.5
- Only the particles on the surface of a solid can collide with other reactants.
- Breaking a solid into powder increases the surface area, so more particles are exposed.
- More collisions per second → more effective collisions → faster reaction.
- Example: powdered marble reacts with HCl faster than a marble chip; powdered catalyst works better.
(b)Describe the main points of the collision theory of reaction rate.4
- Reaction occurs only when reactant particles collide.
- Only collisions with energy ≥ Ea are effective.
- Particles must collide with the correct orientation.
- Rate depends on the number of effective collisions per second.
Q6.(a)Discuss the effect of temperature at which a reaction is carried out.5
- Rate increases with temperature; for many reactions it roughly doubles for each 10°C rise.
- Particles move faster, collide more frequently and with greater energy.
- A larger fraction of particles has energy ≥ Ea, so more effective collisions occur.
- Example: food spoils faster in warm weather than in a refrigerator; Mg burns only when heated.
(b)How does chemical kinetics play an important role in the food industry?4
- Finds the best temperature and conditions for storage and transport (e.g. refrigeration slows spoilage).
- Monitoring ethene predicts ripening and the best time for harvesting.
- Guides preservation methods and control of enzymes in food processing.
- Result: longer shelf life, less waste and better quality.
Q7.(a)Write briefly about the role enzymes play in our body as biological catalysts.5
- Enzymes are protein catalysts made by living cells.
- They speed up body reactions such as digestion and respiration by lowering the activation energy.
- Each enzyme is highly specific (lock-and-key model) and works at body temperature and optimum pH.
- They are not used up. Examples: amylase digests starch; pepsin digests proteins.
(b)Explain the effect of catalyst on a chemical reaction?4
- A catalyst changes the rate without being used up.
- It provides an alternative path with lower activation energy, so more particles can react.
- It does not change the products or the heat of reaction (ΔH).
- Example: Pt or Ni in the addition of H2 to ethene.
