BITSAT Chemistry Chemical Kinetics MCQs

Question: For the reaction H₂(g) + Br₂ (g) → 2HBr (g), the experimental data suggest, rate = k[H₂][Br₂]^1/2. The molecularity and order of the reaction are respectively

a)

b)

c) 1, 1

d)

Answer:

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

Answer: -2

Question: Consider the reaction :

The rate equation for this reaction is rate = k[Cl₂][H₂S]

Which of these mechanisms is/are consistent with this rate equation?

a) B only

b) Both A and B

c) Neither A nor B

d) A only

Answer: A only

Question: In the reaction, P + Q → ? R + S The time taken for 75% reaction of P is twice the time taken for 50% reaction of P. The concentration of Q varies with reaction time as shown in the figure. The overall order of the reaction is 

a) 2

b) 3

c) 0

d) 1

Answer: 1

Question: The unit of rate constant for reactions of second order is

a) L mol^–1s^–1 

b) L^–1 mol s^–1

c) L mol s^–1

d) s^–1

Answer: L mol^–1s^–1 

Question: In a first order reaction with time the concentration of the reactant decreases

a) linearly

b) Exponentially

c) No change

d) None of these

Answer: Exponentially

Question: The decomposition of A follows two parallel first order reactions 

The percentage distribution of B and C are

a) 90 % B and 10 % C

b) 80 % B and 20 % C

c) 60 % B abd 40 % C

d) 76.83% B and 23.17 % C

Answer: 76.83% B and 23.17 % C

Question: A gaseous reaction There is increase in pressure from 100 mm to 120mm in 5 minutes. The rate of disappearance of X₂ is

a) 8 mm min^–1 

b) 2 mm min^–1

c) 16 mm min^–1

d) 4 mm min^–1

Answer: 8 mm min^–1 

Question: Two substances R and S decompose in solution independently, both following first order kinetics. The rate constant of R is twice that of S. In an experiment, the solution initially contained 0.5 millimoles of R and 0.25 of S. The molarities of R and S will be equal just at the end of time equal to

a) Twice the half life of R

b) Twice the half life of S

c) The half life of S

d) The half life of R

Answer: Twice the half life of R

Question: Velocity constant of a reaction at 290 K was found to be 3.2×10^–3. At 300 K it will be

a) 1.28 × 10^–2 

b) 9.6 × 10^–3

c) 6.4 × 10^–3

d) 3.2 × 10^–4

Answer: 6.4 × 10^–3

Question: The addition of a catalyst during a chemical reaction alters which of the following quantities?

a) Entropy

b) Internal energy

c) Enthalpy

d) Activation energy

Answer: Activation energy

Question: During the kinetic study of the reaction, 2A + B→ C + D, following results were obtained:

Based on the above data which one of the following is correct?

a) rate = k [A]² [B]

b) rate = k[A] [B]

c) rate = k[A]²[B]²

d) rate = k[A] [B]²

Answer: rate = k[A] [B]²

Question:  The activation energy for a simple chemical reaction A → B is E_a in forward direction. The activation energy for reverse reaction

a) Is always less than E_a  

b) Can be less than or more than E_a

c) Is always double of E_a 

d) Is negative of E_a

Answer: Can be less than or more than E_a

Question: The following data are for the decomposition of ammonium nitrite in aqueous solution :

The order of reaction is :

a) Zero

b) One

c) Two

d) Three

Answer: One

Question: The chemical reaction proceeds as follows:

 the rate law expression should be

a) r = k[O₃]²

b) r = k [O₃]²[O₂]^–1

c) r = k³ [O₃][O₂]²

d) r = [O₃][O₂]²

Answer: r = k [O₃]²[O₂]^–1

Question: For a reaction A → B, the rate increases by a factor of 2.25 when the concentration of A is increased by 1.5. What is the order of the reaction?

a) 3

b) 0

c) 2

d) 1

Answer: 2

Question: For the reaction system :

2NO (g) + O₂ (g)→2NO₂ (g) volume is suddenly reduced to half of its value by increasing the pressure on it. If the reaction is of first order with respect to O₂ and second order with respect to NO, the rate of reaction will

a) Diminish to one-fourth of its initial value

b) Diminish to one-eighth of its initial value

c) Increase to eight times of its initial value

d) Increase to four times of its initial value

Answer: Increase to eight times of its initial value

Question: For the reaction  the rate law is rate= k[H₂ ][Br₂ ] ^{1/ 2} .

Which of the following statement is true about this reaction?

a) The reaction is of second order

b) Molecularity of the reaction is 3/2

c) The unit of k is s^–1

d) Molecularity of the reaction is 2

Answer: Molecularity of the reaction is 2

Question: The rate law for a reaction between the substances A and B is given by Rate = k [A]ⁿ [B]^m On doubling the concentration of A and halving the concentration of B, the ratio of the new rate to the earlier rate of the reaction will be as

a)

b) (m + n)

c) (n – m)

d) 2^{(n – m)}

Answer: 2^{(n – m)}

Question: The reaction 

a) Bimolecular and second order

b) Unimolecular and first order

c) Bimolecular and first order

d) Bimolecular and zero order

Answer: Bimolecular and first order