CBSE Class 12 Chemistry Chemical Kinetics Worksheet Set A

ONE MARK QUESTIONS

1. Why does the rate of a reaction not remain constant throughout the reaction process? (2010)

2. The rate of a reaction is 1.2 x 10-3 L/mol/s. What is the order of the reaction?

TWO MARK QUESTIONS

1.Define the following terms :

a) Half-life of a reaction (t½)

b) Rate constant (k) (2015)

2.A first order decomposition reaction takes 40 minutes for 30% decomposition. Calculate its t1/2 value. (2008)

3.Show that for a first order reaction, the time required for half the change is independent of initial concentration. (2010)

THREE MARK QUESTIONS

1.A reaction is first order in A and second order in B.

a) Write differential rate equation.

b) How is the rate affected when the concentration of A is tripled?

c) How is the rate affected when the concentration of both A and B are doubled?

2.For a certain chemical reaction, variation in the concentration, ln[R] Vs time(s) plot is given below: ln[R] T(s) For the reaction

a) What is the order of the reaction?

b) Give the relationship between k and t1/2

c) What does the slope of the above line indicate? 

Important Questions for NCERT Class 12 Chemistry Chemical Kinetics

Question. The decomposition of phosphine (PH₃) on tungsten at low pressure is a first-order reaction. It is because the
(a) rate is proportional to the surface coverage
(b) rate is inversely proportional to the surface coverage
(c) rate is independent of the surface coverage
(d) rate of decomposition is very slow.

Question. The rate constant of the reaction A B is 0.6 × 10^–3 mol L–1 s^–1. If the concentration of A is 5 M, then concentration of B after 20 minutes is
(a) 3.60 M
(b) 0.36 M
(c) 0.72 M
(d) 1.08 M 

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. 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. Which one of the following statements for the order of a reaction is incorrect?
(a) Order can be determined only experimentally.
(b) Order is not influenced by stoichiometric coefficient of the reactants.
(c) Order of a reaction is sum of power to the concentration terms of reactants to express the rate of reaction.
(d) Order of reaction is always whole number.

Question. The unit of rate constant for a zero order reaction is
(a) mol L^–1 s^–1
(b) L mol^–1 s^–1
(c) L2 mol^–2 s^–1
(d) s^–1

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. 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. If the rate of the reaction is equal to the rate constant, the order of the reaction is
(a) 0
(b) 1
(c) 2
(d) 3 

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.

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