Assertion Reason Chemistry Chapter 3 Chemical Kinetics
Questions of Assertion Reason of Chemistry Chapter 3 Chemical Kinetics CBSE Class 12 are very simple to understand as this chapter deals with Chemical Kinetics. To solve assertion reason type questions of Chemistry, a deeper understanding of concept about Rate of a Chemical Reaction, Factors Influencing Rate of a Reaction, Integrated Rate Equations, Temperature Dependence of the Rate of a Reaction and Collision Theory of Chemical Reactions is required. In order to help the student in solving Assertion Reason type of questions, detailed process is explained.
How to solve Assertion Reason Type Questions?
In Assertion-Reason type of question, two statements are given, first is Assertion and second is called Reason. Student must have to think critically about both the statements in Assertion Reason Questions, since it combines multiple choice questions and true/false type of questions which requires a higher level of understanding.
How many types are there of Assertion Reason Type Questions?
Assertion-Reason type of questions can be asked either with four MCQ options or with five MCQ options. First four options are same in both the cases only one more options is being provided i.e. last one. One extra option increases the difficulty level of the questions.
In assertion reason type of questions, all 4 or 5 options are same for each question, which are as:
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
(e) Both Assertion and Reason are false.
Then a question haunts in every student’s mind, which option is correct and when?
This can be understood clearly with the following table:
| Assertion (A) | Reason (R) | MCQ Options (Fixed for all questions) |
|---|---|---|
| If True | True | (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A). |
| If True | True | (b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A). |
| If True | False | (c) Assertion (A) is true but reason (R) is false. |
| If False | True | (d) Assertion (A) is false but reason (R) is true. |
| If False | False | (e) Both Assertion and Reason are false. |
Now, lets practice some Assertion Reason Questions of Chemistry: Chapter 3 Chemical Kinetics
Read instructions carefully before answering the questions.
For question given below, two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both A and R are true and R is correct explanation of the assertion.
(b) Both A and R are true but R is not the correct explanation of the assertion.
(c) A is true but R is false.
(d) A is false but R is true.
Question.1.
Assertion (A) : Instantaneous rate is used to predict the rate of a reaction at a particular moment of time.
Reason (R) : Average rate is constant for the time interval for which it is calculated.
Ans.1. (b)
Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
Question.2.
Assertion (A) : For the reaction, CHCl_{3}+Cl_{2} \rightarrow CCl_{4}+HCl , rate =k[CHCl_{3}]+[Cl_{2}]^{\frac{1}{2}} .
Reason (R) : Rate law for any reaction can be predicted with the help of a balanced
chemical equation.
Ans.2. (c)
Assertion (A) is correct, but Reason (R) is incorrect statement.
Question.3.
Assertion (A) : The rate of the reaction is the rate of change of concentration of a reaction or a product.
Reason (R) : Rate of reaction remains constant during the course of reaction.
Ans.3. (c)
Assertion (A) is correct, but Reason (R) is incorrect statement.
Question.4.
Assertion (A) : Order of the reaction can be zero or fractional.
Reason (R) : We cannot determine order from balanced chemical equation.
Ans.4. (b)
Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
Question.5.
Assertion (A) : Order and molecularity are same.
Reason (R) : Order is determined experimentally and molecularity is the sum of the stoichiometric coefficient of rate determining elementary step.
Ans.5. (d)
Assertion (A) is incorrect, but Reason (R) is correct statement.
Question.6.
Assertion (A) : For the reaction:
2N_{2}O_{5} \rightarrow 4NO_{2}+O_{2} .
Rate = k[N_{2}O_{5}]
Reason (R) : Rate of decomposition of N_{2}O_{5} is determined by slow step.
Ans.6. (b)
Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
Question.7.
Assertion (A) : The inversion of cane sugar, 
Reason (R) : H_{2}O in this reaction is present in very less amount as compared to C_{12}H_{22}O_{11} .
Ans.7. (c)
Assertion (A) is correct, but Reason (R) is incorrect statement.
Question.8.
Assertion (A) : For each ten degree rise of temperature the specific rate constant is nearly doubled.
Reason (R) : Energy-wise distribution of molecules in a gas is an experimental function of temperature.
Ans.8. (b)
Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
Question.9.
Assertion (A) : If the activation energy of a reaction is zero, temperature will have no effect on the rate constant.
Reason (R) : Lower the activation energy, faster is the reaction.
Ans.9. (c)
Assertion (A) is correct, but Reason (R) is incorrect statement.
Question.10.
Assertion (A) : Rate constants determined from Arrhenius equation are fairly accurate for simple as well as complex molecules.
Reason (R) : Reactant molecules undergo chemical change irrespective of their orientation during collision.
Ans.10. (c)
Assertion (A) is correct, but Reason (R) is incorrect statement.
Question.11.
Assertion (A) : The enthalpy of reaction remains constant in the presence of a catalyst.
Reason (R) : A catalyst participating in the reaction, forms different activated complex and lowers down the activation energy but the difference in energy of reactant and product remains the same.
Ans.11. (a)
Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
Question.12.
Assertion (A) : All collision of reactant molecules lead to product formation.
Reason (R) : Only those collisions in which molecules have correct orientation and sufficient kinetic energy lead to compound formation.
Ans.12. (d)
Assertion (A) is incorrect, but Reason (R) is correct statement.
