Chemical Kinetics: Assertion Reasoning Type Questions For CBSE Exam Worksheet
Assertion Reasoning Type Questions
Read the statements given as assertion & reason both and choose the correct option as per the following instructions. (A) if both assertion & reason are correct statements and reason is the correct explanation of assertion. (B) if both assertion & reason are correct statements and reason is not the correct explanation of assertion. (C) if the assertion is the correct statement & the reason is an incorrect statement. (D) if the assertion is incorrect statement and reason is the correct statement.
1.Assertion: The order of reaction can be zero or fractional. Reason: The order of a reaction cannot be determined from a balanced chemical reaction. Ans 1. B
2.Assertion: The order and molecularity of a reaction are always the same. Reason: Order is determined experimentally whereas molecularity by a balanced elementary reaction. Ans 2. D
3.Assertion: Rate constant of a zero-order reaction has the same unit as the rate of a reaction. Reason: Rate constant of a zero-order reaction does not depend upon the concentration of the reactant. Ans 3. A
4.Assertion: In a first-order reaction, the concentration of the reactant is doubled, its half-life is also doubled. Reason: The half-life of a reaction does not depend upon the initial concentration of the reactant in a first-order reaction. Ans 4. D
5. Assertion: Average rate and instantaneous rate of a reaction have the same unit. Reason: Average rate becomes an instantaneous rate when the time interval is too small. Ans 5. B
6. Assertion: Hydrolysis of methyl ethanoate is a pseudo-first-order reaction. Reason: Water is present in large excess and therefore its concentration remained constant throughout the reaction. Ans 6. A
7. Assertion: The order of a reaction can be zero. Reason: In the case of heterogeneous catalysis, the reaction becomes independent of concentration at a high concentration of the reaction. Ans 7. A
8. Assertion: The slowest elementary step in a complex reaction decides the rate of the reaction. Reason: The slowest elementary step always has the smallest molecularity. Ans 8. C
9. Assertion: A catalyst increases the rate of a reaction. Reason: The catalyst increases the activation energy which in turn increases the rate of the reaction. Ans 9. C
10. Assertion: Activation complex for the forward reaction will have lower energy than that for the backward reaction in an exothermic reaction. Reason: Reactants have greater energy than products for an exothermic reaction. Ans 10. D
11. Assertion: Increase in temperature increases the rate of reaction. Reason: More colliding molecules will have energy greater than threshold energy. Ans 11. A
12. Assertion: The unit of the rate constant is independent of the order of the reaction. Reason: The power of concentration terms in the rate equation keeps changing with change in order. Ans 12. D
13. Assertion: Increase in concentration of reactant will not change the rate for a zero-order reaction. Reason: Rate constant for a zero-order reaction is a constant for a particular initial concentration. Ans 13. B
14. Assertion: Complex reaction takes place in different steps and the slowest step determines the rate of reaction. Reason: The order and molecularity of a reaction are always equal. Ans 14. C
15. Assertion: The rate of reaction increases with an increase in temperature. Reason: The number of effective collisions increases with an increase in temperature. Ans 15. A
16. Assertion: The order of a reaction with respect to any reactant or product can be zero, positive, negative, and fractional. Reason: The rate of a reaction cannot decrease with an increase in the concentration of a reactant or product. Ans 16. C
17. Assertion: The rate of a reaction sometimes does not depend on concentration. Reason: Lower the activation energy faster is the reaction. Ans 17. B
18. Assertion: For a certain reaction, a large fraction of molecules have energy more than the threshold energy, still the rate of reaction is very slow. Reason: The colliding molecules must not be properly oriented for effective collisions. Ans 18. A
