MCQs for NCERT Class 12 Chemistry Chapter 4 Chemical Kinetics

Please refer to the MCQ Questions for Class 12 Chemistry Chapter 4 Chemical Kinetics with Answers. The following Chemical Kinetics Class 12 Chemistry MCQ Questions have been designed based on the latest syllabus and examination pattern for Class 12. Our experts have designed MCQ Questions for Class 12 Chemistry with Answers for all chapters in your NCERT Class 12 Chemistry book.

Chemical Kinetics Class 12 MCQ Questions with Answers

See below Chemical Kinetics Class 12 Chemistry MCQ Questions, solve the questions and compare your answers with the solutions provided below.

Question. The rate constant of first order reaction is 3 × 10^–6 per second. The initial concentration is 0.10 M.
The initial rate is:
(a) 3 × 10^–7 mol/litre/sec
(b) 3 × 10^–8 mol/litre/sec
(c) 3 × 10^–5 mol/litre/sec
(d) 3 × 10^–8 mol/litre/sec

Question. The half-life of a substance in a certain enzymecatalysed reaction is 138 s. The time required for the concentration of the substance to fall from 1.28 mg L^–1 to 0.04 mg L^–1 is
(a) 414 s
(b) 552 s
(c) 690 s
(d) 276 s 

Question. Half-life period of a first order reaction is 1386 seconds. The specific rate constant of the reaction is
(a) 0.5 × 10–2 s^–1
(b) 0.5 × 10–3 s^–1
(c) 5.0 × 10–2 s^–1
(d) 5.0 × 10–3 s^–1 

Question. The activation energy for a simple chemical reaction A ⇌ B is Ea in forward direction. The activation energy for reverse reaction
(a) is negative of Ea
(b) is always less than Ea
(c) can be less than or more than Ea
(d) is always double of Ea. 

Question. When a biochemical reaction is carried out in laboratory, outside the human body in absence of enzyme, then rate of reaction obtained is 10^–6 times, the activation energy of reaction in the presence of enzyme is
(a) 6/RT
(b) P is required
(c) different from Ea obtained in laboratory
(d) can’t say anything. 

Question. Which of the following statement is true for the reaction, H₂ + Br₂ →2HBr . The rate law is [ H₂ ][ Br₂ ]1/ 2 dx/dt=k  
(a) order of reaction is 1.5
(b) molecularity of the reaction is 2
(c) by increasing the concentration of Br₂ four times the rate of reaction is doubled
(d) all the above are correct.

Question. In a reaction, A + B → product, rate is doubled when the concentration of B is doubled, and rate increases by a factor of 8 when the concentration of both the reactants (A and B) are doubled, rate law for the reaction can be written as
(a) rate = k[A][B]²
(b) rate = k[A]²[B]²
(c) rate = k[A][B]
(d) rate = k[A]²[B]

Question. For the reaction : H₂ Cl₂ →^sunlight 2HCl the order of reaction is 
(a) 0
(b) 2
(c) 1
(d) 3

Question. The rate of a first order reaction is 1.5 × 10^–2 mol L^–1 min^–1 at 0.5 M concentration of the reactant. The half-life of the reaction is
(a) 0.383 min
(b) 23.1 min
(c) 8.73 min
(d) 7.53 min

Question. Activation energy of a chemical reaction can be determined by
(a) evaluating rate constants at two different temperatures
(b) evaluating velocities of reaction at two different temperatures
(c) evaluating rate constant at standard temperature
(d) changing concentration of reactants. 

Question. By the action of enzymes, the rate of biochemical reaction
(a) does not change
(b) increases
(c) decreases
(d) either (a) or (c).

Question. The reaction A B follows first order kinetics. The time taken for 0.8 mole of A to produce 0.6 mole of B is 1 hour. What is the time taken for conversion of 0.9 mole of A to produce 0.675 mole of B ?
(a) 1 hour
(b) 0.5 hour
(c) 0.25 hour
(d) 2 hours

Question. For reaction aA→ xP , when [A] = 2.2 mM, the rate was found to be 2.4 mMs–1. On reducing concentration of A to half, the rate changes to 0.6 mMs–1. The order of reaction with respect to A is : 
(a) 1.5
(b) 2.0
(c) 2.5
(d) 3.0

Question. For the reaction, A + B → products, it is observed that
(i) on doubling the initial concentration of A only, the rate of reaction is also doubled and
(ii) on doubling the initial concentration of both A and B, there is a change by a factor of 8 in the rate of the reaction.
The rate of this reaction is given by
(a) rate = k[A][B]²
(b) rate = k[A]²[B]²
(c) rate = k[A][B]
(d) rate = k[A]²[B]

Question. For a first order reaction, to obtain a positive slope, we need to plot {where [A] is the concentration of reactant A} 
(a) – log₁₀[A] vs t
(b) – loge[A] vs t
(c) log₁₀[A] vs log t
(d) [A] vs t

Question. T50 of first -order reaction is 10 min. Starting with 10 mol L^–1, rate after 20 min is 
(a) 0.0693 mol L^–1 min^–1
(b) 0.0693 × 2.5 mol L^–1 min^–1
(c) 0.0693 × 5 mol L^–2 min^–1
(d) 0.0693 × 10 mol L^–1 min^–1

Question. The first order rate constant for a certain reaction increases from 1.667 × 10–6 s^–1 at 727ºC to 1.667 × 10^–4 s^–1 at 1571ºC. The rate constant at 1150ºC, assuming constancy of activation energy over the given temperature range is
[Given : log 19.9 = 1.299] 
(a) 3.911 × 10^–5 s^–1
(b) 1.139 × 10^–5 s^–1
(c) 3.318 × 10^–5 s^–1
(d) 1.193 × 10^–5 s^–1

Question. For a reaction between A and B the order with respect to A is 2 and the order with respect to B is 3.
The concentrations of both A and B are doubled, the rate will increase by a factor of
(a) 12
(b) 16
(c) 32
(d) 10

Question. Chemical reactions with very high E_a values are generally
(a) very fast 
(b) very slow
(c) moderately fast
(d) spontaneous       

Question. The energies of activation for fo1ward and reverse reactions for A₂ + B₂ ⇌ 2AB are 180 kJ mol^-1 and 200 kJ mol^-1 respectively. The presence of a catalyst lowers the activation energy ofboth (forward and reverse) reactions by 100 kJ mol^-1. The enthalpy change of the reaction ( A₂ + B₂ ➔ 2AB) in the presence of catalyst will be (in kJ mol^-1)
(a) 300
(b) 120
(c) 280
(d) 20     

Question. According to Arrhenius equation, the rate constant (k) is related to temperature (T) as    

Question. For the two gaseous reactions, following data are given
A → B; k₁ = 10¹⁰ e^– 20,000/T
C → D; k₂ = 10¹² e^– 24,606/T
the temperature at which k₁ becomes equal to k₂ is
(a) 400K
(b) 1000 K
(c) 800K 
(d) 1500 K
(e) 500 K   

Question. A chemical reaction proceeds following formula k = PZe^{– E_a / RT} . Which of the following process will increase the rate of reaction ? 
(a) Lowering of E_a
(b) Lowering of P
(c) Lowering of Z
(d) Independent of all the above factors   

Question. The rate of reaction increases with temperature due to
(a) decrease in activation energy
(b) increase in activation energy
(c) increase in collision frequency
(d) increase in concentration     

Question. Temperature coefficient of a reaction is 2. When temperature is increased from 30°C to 100°C, rate of the reaction increases by 
(a) 128 times
(b) 100 times
(c) 500 times
(d) 250 times     

Question. The reason for almost doubling the rate of reaction on increasing the temperature of the reaction system by 10°C is
(a) the value of threshold energy increases 
(b) collision frequency increases
(c) the fraction of the molecule having energy equal to threshold energy increases
(d) activation energy decreases   

Question. With increase in temperature, rate of reaction
(a) increases 
(b) decreases
(c) remains same
(d) may increase or decrease       

Question. Which increases on increase of temperature ? 
(a) Energy of activation (E_a)
(b) Collision frequency (Z)
(c) Rate constant (k)
(d) Both (b) and (c)       

Question. Rate of a reaction can be expressed by Arrhenius equation as k = Ae^{– E_a / RT} In th is equation, E represents
(a) the energy above which all the colliding molecules will react
(b) the energy below which colliding molecules will not react
(c) the total energy of the reacting molecuJes at a temperature, T
(d) the fraction of molecules with energy greater than the activation energy of the reaction       

Question. The minimum energy required for the reacting molecules to undergo reaction is 
(a) potential energy
(b) kinetic energy
(c) thermal energy
(d) activation energy     

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

Question. The temperature dependence of rate constant (k) of a chemical reaction is written in tem1s of Arrhenius equation, k = Ae^{– E_a / RT} . Activation energy (E*) of the reaction can be calculated by plotting 
(a) log k vs 1 / T
(b) log k vs 1 / log
(c) k vs T
(d) k vs 1 / log       

Question. Temperature dependent equation can be written as 
(a) In k = In A – e^{E_a / RT}
(b) Ink = In A + e^{E_a / RT}
(c) Ink = In A – e^{RT / E_a} 
(d) None of these       

Question. Consider an endothermic reaction X → Y with the activation energies E_b and E_f for the backward and forward reactions respectively. In general 
(a) there is no definite relation between E_b and E_f
(b) E_b = E_f
(c) E_b > E_f
(d) E_b < E_f       

Question. Unit of frequency factor (A) is 
(a) mol/L
(b) mol/L x s
(c) depends upon order of reaction
(d) it does not have any unit   

Question. Arrhenius equation is
(a) ΔH = ΔE + Δn_g RT
(b) ΔG = ΔH – T . ΔS
(c) k = Ae^{– E_a / RT}
(d) None of these     

Question. Activation energy of a reaction
(a) is independent of temperature
(b) increases with temperature
(c) gets doubled for every 10 degree rise in temperature
(d) decreases with temperature       

Question. In the respect of the equation k = Ae^{– E_a / RT}  in chemical kinetics, which one of the following statements is correct ?
(a) K is equilibrium constant 
(b) A is adsorption factor
(c) E_a is energy of activation
(d) R is Rydberg constant       

Question. When initial concentration of the reactant is doubled, the half-life period of a zero order reaction
(a) is halved
(b) is doubled
(c) is tripled
(d) remains unchanged.

Question. A first order reaction has a specific reaction rate of 10^–2 sec^–1. How much time will it take for 20 g of the reactant to reduce to 5 g?
(a) 138.6 sec
(b) 346.5 sec
(c) 693.0 sec
(d) 238.6 sec 

Question. In most cases, for a rise of 10K temperature the rate constant is doubled to tripled. This is due to the reason that
(a) collision frequency increases by a factor of 2 to 3.
(b) fraction of molecules possessing threshold energy increases by a factor of 2 to 3
(c) Activation energy is lowered by a factor of 2 to 3.
(d) none of these

Question. The rate constant for the reaction, 2N₂O₅ →4NO₂ +O₂ is 3.0×10^-4 s^-1 . If start made with 1.0 mol L^–1 of N₂O₅, calculate the rate of formation of NO₂ at the moment of the reaction when concentration of O₂ is 0.1 mol L^–1.
(a) 2.7 x10^-4 molL^-1s^-1 
(b) 2.4×10^-4  molL^-1s-1
(c) 4.8×10^-4  molL^-1s-1
(d) 9.6×10^-4  molL^-1s-1

Question. A reaction which is of first order w.r.t. reactant A, has a rate constant 6 min–1. If we start with [A] = 0.5 mol L^–1, when would [A] reach the value of 0.05 mol L^–1
(a) 0.384 min
(b) 0.15 min
(c) 3 min
(d) 3.84 min

Question. The rate of reaction between two reactants A and B decreases by a factor of 4 if the concentration of reactant B is doubled. The order of this reaction with respect to reactant B is
(a) 2
(b) –2
(c) 1
(d) –1

Question. Half-lives of a first order and a zero order reaction are same. Then the ratio of the initial rates of first order reaction to that of the zero order reaction is 
(a) 1/0.693
(b) 2 × 0.693
(c) 0.693
(d) 2/0.693

Question. The rate constant for a first order reaction is 4.606 × 10^–3 s^–1. The time required to reduce 2.0 g of the reactant to 0.2 g is
(a) 100 s
(b) 200 s
(c) 500 s
(d) 1000 s 

Question. If the rate constant for a first order reaction is k, the time (t) required for the completion of 99% of the reaction is given by
(a) t = 2.303/k
(b) t = 0.693/k
(c) t = 6.909/k
(d) t = 4.606/k

Question. Collision theory is used to explain how chemical species undergo a reaction. Using this theory and the kinetic molecular model, which of the following does NOT influence the rate of a chemical reaction?
(a) The temperature of the system
(b) The geometry or orientation of the collision
(c) The velocity of the reactants at the point of collision
(d) All of the above influence the rate

Question. For the following reaction: NO₂(g) + CO(g) → NO(g) + CO₂(g), the rate law is: Rate = k [NO₂]₂.
If 0.1 mole of gaseous carbon monoxide is added at constant temperature to the reaction mixture which of the following statements is true?
(a) Both k and the reaction rate remain the same
(b) Both k and the reaction rate increase
(c) Both k and the reaction rate decrease
(d) Only k increases, the reaction rate remain the same

Question. 2A B → C, It would be a zero order reaction when
(a) the rate of reaction is proportional to square of concentration of A
(b) the rate of reaction remains same at any concentration of A
(c) the rate remains unchanged at any concentration of B and C
(d) the rate of reaction doubles if concentration of B is increased to double.

Question. The addition of a catalyst during a chemical reaction alters which of the following quantities?
(a) Enthalpy
(b) Activation energy
(c) Entropy
(d) Internal energy

Question. What is the activation energy for a reaction if its rate doubles when the temperature is raised from 20 °C to 35 °C? (R = 8.314 J mol^–1 K^–1)
(a) 34.7 kJ mol^–1
(b) 15.1 kJ mol^–1
(c) 342 kJ mol^–1
(d) 269 kJ mol^–1