CBSE Class 12 Chemistry Chemical Kinetics Worksheet Set C

Question. According to arrhenius equation, the slope of log k vs 1/T plot is:
a. - E_a/2.303R
b. - E_a/2.303
c. - E_a/2.303RT
d. - E_a/2.303RT

Answer: A

Question. According to arrhenius hypothesis, rate of reaction increases with:
a. Rise in temperature
b. Decrease in temperature
c. Rise in pressure
d. Decrease in pressure

Answer: A

Question. A reaction having equal energies of activation for forward and reverse reaction has:
a. ΔS = 0
b. ΔG = 0
c. ΔH = 0
d. ΔH = ΔG = ΔS = 0

Answer: C

Question. The effect of temperature on reaction rate is shown by:
a. Kirchoff's equation
b. Arrhenius equation
c. Gibb's- Helmhoitz equation
d. Clausius- Clapeyron equation

Answer: B

Question. The rate constant of a first order reaction at 27°C is 10^–3 min^–1. The rate constant (in min^-1) at 17°C for this reaction?
a. 10^–3
b. 5 × 10^–4
c. 2 × 10^–3
d. 10²

Answer: B

Question. N₂ (g) + 3H₂ (g) ⇄ 2NH₃ (g) + 22 kcal the activation energy for forward reaction is 50kcal. What is the activation energy for the backward reaction?
a. –72 kcal
b. –28 kcal
c. + 28 kca
d. +72 kcal

Answer: D

Question. Chemical reaction with high E_a values are generally:
a. Very fast
b. Very slow
c. Moderately fast
d. Spontaneous

Answer: B

Question. In the presence of a catalyst, activation energy of a reaction is lowered by 2 kcal at 27°C. Hence, rate will be:
a. 20 times
b. 28 times
c. 14 times
d. Remain same

Answer: B

Question. The activation energy of a reaction at a give temperature is found to be 2.303 RTJmol^–1 . The ratio of rate constant (K) to the arrhenius factor (A) is:
a. 0.01
b. 0.1
c. 0.02
d. 0.001

Answer: B

Question. The threshold energy of a chemical reaction depends upon
a. Nature of reacting species
b. Temperature
c. Concentration of species
d. Number of collisions

Answer: A

Question. Activation energy is ________ to rate of reaction
a. Directly proportional
b. Inversely proportional
c. Equal
d. Not related

Answer: B

Question. The rate of a reaction can be increased in general by all the factors except
a. Using a catalyst
b. Increasing the temperature
c. Increasing the activation energy
d. Increasing the concentration of reactants

Answer: C

Question. The energy of activation of positive catalyzed reaction as compared to that of an uncatalyzed reaction is
a. More
b. Less
c. Same
d. May be more or less

Answer: B

Question. The increase in concentration of the reactants lead to change in:
a. ΔH
b. Collision frequency
c. Activation energy
d. Equilibrium constant

Answer: B

Question. Which of the following statement is incorrect about the collision theory of chemical reaction?
a. It considers reacting molecules or atoms to be hard spheres and ignores their structure features.
b. Number of effective collisions determine the rate of reaction
c. Collision of atoms or molecules possessing sufficient threshold energy result into the product formation
d. Molecules should collide with sufficient threshold energy and proper orientation for the collision to be effective

Answer: C

Question. Threshold energy is equal to:
a. Activation energy
b. Activation energy – energy of molecules
c. Activation energy + energy of molecules
d. None of the options

Answer: C

Question. Which of the following statement is not correct for the catalyst?
a. It catalyses the forward and backward reaction to the same extent.
b. It alters ΔG of the reaction
c. It does not change the equilibrium constant of a reaction
d. It provides an alternate mechanism by reducing activation energy between reactants and products.

Answer: B

Question. The rate constant is given by the equation K = PZe^–Ea/RT which factor should register a decrease for the reaction to proceed more rapidly?
a. T
b. Z
c. Ea
d. P

Answer: C

Question. In the presence of a catalyst, the heat evolved or absorbed during the reaction:
a. Increases
b. Decreases
c. Remain unchanged
d. May increase or decrease

Answer: C

Question. For a certain reaction a large fraction of molecules has energy more than the threshold energy, still the rate of reaction is very slow. The possible reason for this could be that:
a. The colliding molecules could be large in size
b. The colliding molecules must not be properly oriented for effective collisions.
c. The rate of reaction could be independent of the energy
d. One of the reactant could be in excess

Answer: B

Question. Rate of a general reaction A + B → Products can be expressed as follows on the basis of collision theory.Rate = Z_ABe^–Ea/RT Which of the following statement is not correct for the above expression?
a. Z is collision frequency and is equal to number of collisions per second per unit volume of the reaction mixture
b. e–Ea/RT is the fraction of molecules with kinetic energy equal to or greater than E_a.
c. Ea is activation energy of the reaction
d. All the molecules which colloid with one other are effective collisions

Answer: D

Question. The role of a catalyst is to change:
a. Gibbs energy
b. Enthalpy of reaction
c. Activation energy of reaction
d. Equilibrium constant

Answer: C

Question. The rate constant, activation energy and Arrhenius parameter of a chemical reaction at 25 °C are 3.0 × 10^–4 s^–1, 104.4 kJ mol^–1 and 6.0 × 10¹⁴ s^–1 respectively. The value of the rate constant as T → ∞ is
a. 2.0 × 10¹⁸ s^–1
b. 6.0 × 10¹⁴ s^–1
c. Infinity
d. 3.6 × 10³⁰ s^–1

Answer: B

 

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