# Assertion-Reason Questions on Chemical Kinetics – Chapter 4 CBSE Class 12 Chemistry

#### Assertion-Reason Questions on Chemical Kinetics

###### (d) Assertion (A) is incorrect, but Reason (R) is correct statement.

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.

2. Assertion (A) : For the reaction, CHCl3 + Cl2  —–> CCl4 + HCl, rate = k[CHCl3] [Cl2] 1/2

Reason (R) : Rate law for any reaction can be predicted with the help of a balanced chemical equation.

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.

4. Assertion (A) : Order of the reaction can be zero or fractional.

Reason (R) : We cannot determine order from balanced chemical equation.

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.

6. Assertion (A) : For the reaction 2N2O5 —–> 4NO2 + O2 ; Rate = k[N2O5]

Reason (R) : Rate of decomposition of N2O5 is determined by slow step.

7. Assertion (A) : The inversion of cane sugar, C6 H12 O11 + H2 O —–> C6 H12 O6 + C6 H12 O6 ­ is a pseudo first order reaction.

Reason (R) : H2O in this reaction is present in very less amount as compared to C12H22O11.

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.

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.

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.

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.

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.