Chemical Kinetics MCQs Mock Test of Class 12th Chemistry

Welcome to your Chemical Kinetics MCQs Mock Test of Class 12th Chemistry

1.

Question 1. The rate constant for the reaction 2N2O5 → 4NO2 + O2 is 3.0 × 10-5 sec-1. If the rate is 2.40 × 10-5 mol litre-1 sec-1, then the concentration of N2O5 (in mol litre-1) is:

(a) 1.4

(b) 1.2

(c) 0.04

(d) 0.8

2.

Question 2. When a biochemical reaction is carried out in laboratory from outside of human body in absence of enzyme, then the rate of reaction obtained is 10-6 times, then activation energy of reaction in presence of enzyme is:

(a) 6/RT

(b) Pis required

(c) Different from Ea obtained in the laboratory

(d) Cannot, say anything

3.

Question 3. If ‘I’ is the intensity of absorbed light and ‘C’ is the concentration of AB for the photochemical process AB + hv → AB+, the rate of formation of AB* is directly proportional to:

(a) C

(b) l

(c) l2

(d) Cl.

4.

Question 4. In the following reaction, how is the rate of appearance of the underlined product related to the rate of disappearance of the underlined reactant? BrO−3 (aq) + 5 Br– +6H+ → 3 Br2 (1) + 3H2O (l)

(a) d[Br2]dt = -d [Br–]/dt

(b) d[Br2]dt = 35 d[Br−]dt

(c) d [Br2]/dt = 35

d [Br–]/dt

5.

Question 5. For a chemical reaction, X + 2Y → Z, if the rate of appearance of Z is 0.50 moles per litre per hour, then the rate of disappearance of Y is

(a) 0.5 mol L-1 hr-1

(b) 1.0 mol L-1 hr-1

(c) 0.25 mol L-1 hr-1

(d) cannot be predicted

6.

Question 6. For the reaction, NO2 (g) + CO (g) → NO (g), the correct expression for the rate of the reaction is

(a) rate = −d[NO2]dt

(b) rate = −d[CO2]dt

(c) rate = d[NO2]−d[CO]dt

(d) rate = d[CO2]dt

7.

Question 7. The rate of a reaction is primarily determined by the slowest step. This step is called

(a) rate determining step

(b) activation step

(c) reaction rate step

(d) none of these.

8.

Question 8. The reaction of high molecularity are rare because

(a) Many body collisions have a low probability.

(b) Many body collisions are not favoured energetically.

(c) Activation energy of many body collisions is very large

(d) Very high concentration is required for such reactions.

9.

Question 9. For a chemical reaction A → B, it is found that the rate of the reaction quardruples when the concentration of A is doubled. The rate expression for the reaction is, rate = k [A]n where the value of n is

(a) 1

(b) 2

(c) 0

(d) 3

10.

Question 10. On increasing the temperature of the reacting system by 10° the rate of reaction almost becomes double. The most appropriate reason for this is that

(a) Activation energy decreases by increases of temperature

(b) The fraction of molecules having threshold energy increases

(c) Collision frequency increases

(d) The value of threshold energy decreases.

11.

Question 11. The half-life period of any first order reaction

(a) is half the specific rate constant

(b) is always the same irrespective of the reaction

(c) is independent of initial concentration

(d) in directly proportional to initial concentration of reactants.

12.

Question 12. The dimensions of rate constant of 2nd order reaction involves

(a) concentration

(b) concentration and time

(c) time only

(d) neither time nor concentration.

13.

Question 13. A zero order reaction A → Products, has rate constant 10-2 mole L-1 s-1. If a process is started with 10 moles of A in a one litre vessel, the number of moles of reactant after 10 minutes will be

(a) 10

(b) 5

(c) 6

(d) 4.

14.

Question 14. For which of the following reactions, the temperature coefficient is maximum?

(a) A → B : Ea = 50 kJ

(b) P → Q : Ea = 40 kj

(c) X → Y : Ea = 60kJ

(d) W → Z : Ea = 80kJ

15.

Question 15. A hypothetical reaction 2p + q → s + r has rate constant as 2.0 × 10-3 mol L-1 s-1. The order of the reaction is

(a) unpredictable

(b) zero

(c) one

(d) two

16.

Question 16. The ratio t7/8 : t1/2 for the first order is

(a) 3

(b) 5

(c) 2

(d) 7

17.

Question 17. The molecularity of the reaction cannot be

(a) 1

(b) 2

(c) 1.5

(d) 3.

18.

Question 18. For the first order reaction, the half-life is independent of

(a) catalyst

(b) temperature

(c) both catalyst and temperature

(d) initial concentration of reactants.

19.

Question 19. For a certain reaction aA → bB, the rate of reaction is doubled when the concentration of A is increased by four times. The rate ot reaction is equal to

(a) k[A]a

(b) k[A]1/2

(c) k[A]1/a

(d) k[A].

20.

Question 20. The half life period of 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

21.

Question 21. The rate constant of a reaction A → B is 0.6 × 103 mole per second. If the concentration of [A] is 5 M, then what will be concentration of [B] after 20 months?

(a) 0.36 M

(b) 0.72 M

(c) 1.08 M

(d) 3.60 M

22.

Question 22. Which of the following is affected by catalyst?

(a) ∆H

(b) ∆S

(c) ∆G

(d) Ea

23.

Question 23. A first order reaction has specific reaction rate 10-2s-1. How much time it will take for 20g of reactant to reduce to 5g?

(a) 138.6 s

(b) 346.5 s

(c) 693.0 s

(d) 238.6 s

24.

Question 24. The rate law for the chemical reaction, 2NO2Cl → 2NO2 + Cl2 is r = k[NO2Cl]. Which of the following is rate controlling step?

(a) NO2 + Cl → NO2Cl

(b) NO2Cl + Cl → NO2 + Cl2

(c) NO2Cl → NO2 + Cl

(d) 2NO2Cl → 2NO2 + Cl2.

25.

Question 25. Rate constant of a reaction depends upon

(a) Temperature

(b) time

(c) initial concentration

(d) none

26.

Question 26. DDT on exposure to water decomposes. Half-life = 10 years. How much time will it take for its 90% decomposition?

(a) 50 years

(b) 70 years

(c) 500 years

(d) 700 years.

27.

Question 27. 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 mm

(b) 23.1mm

(c) 8.73 mm

(d) 7.53 mm

28.

Question 28. The rate equation for the reaction 2A + B → C is found to be: rate = k [A] [B]. The correct statement inxelation to this reaction is that the

(a) unit of R must be s-1

(b) t1/2 is constant

(c) rate of formation of C is twice the rate of disappearance of A.

(d) value of k is independent of the initial concentration of A and B.

29.

Question 29. The reaction 2 SO2 (g) + O2 (g) ⇌ SO3 (g) is carried out in 1 dm³ vessel and 2 dm³ vessel separately. The ratio of the reaction velocities will be

(a) 1 : 8

(b) 1 : 4

(c) 4 : 1

(d) 8 : 1

30.

Question 30. A + 2B → C + D. If- d [A]/dt = 5 × 10-4 mol L-1 s-1, Then – d[B]dtis

(a) 2.5 × 10-4 mol L-1 s-1

(b) 5.0 × 10-4 mol L-1 s-1

(c) 2.5 × 10-3 mol L-1 s-1

(d) 1.0 × 10-3 mol L-1 s-1

31.

Question 31. Which of the following statements is not correct for order of a reaction?

(a) Order of a reaction can be determined experimentally.

(b) It is the sum of the powers of concentration terms in the rate law expression.

(c) It does not necessarily depend on the stoichiometric coefficients.

(d) Order of a reaction cannot be fractional.

32.

Question 32. t1/4 can be taken as the time taken for the concentration of a reactant to drop to 3/4 of its initial value. If the rate constant for a first order reaction is K, then t1/4 can be written as

(a) 0.10/K

(b) 0.29/K

(c) 0.69/K

(d) 0.73/K

33.

Question 32. t1/4 can be taken as the time taken for the concentration of a reactant to drop to 3/4 of its initial value. If the rate constant for a first order reaction is K, then t1/4 can be written as

(a) 0.10/K

(b) 0.29/K

(c) 0.69/K

(d) 0.73/K

34.

Question 34. 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.

35.

Question 35. The potential energy diagram in the reaction R → P is given. ∆H° of the reaction corresponds to the energy.

(a) a

(b) b

(c) c

(d) a + b

36.

Question 36. 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 the reactant B is

(a) 2

(b) -1

(c) 1

(d) -2

37.

Question 37. For reaction aA → xP, when [A] = 2.2 mM the rate was found to be 2.4 mMs-1. On reducing the 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

38.

Question 38. The half-lives of two samples are 0.1 and 0.4 second. Their respective concentrations are 200 and 50 respectively. What is the order of the reaction?

(a) 0

(b) 2

(c) 1

(d) 4

39.

Question 39. In a first order reaction, the concentration of the reactant decreases from 800 mol/dm³ to 50 mol/dm³ in 2 × 104 sec. The rate constant for the reaction in sec-1

(a) 2 × 104

(b) 3.45 × 10-5

(c) 1.386 × 10-4

(d) 2 × 10-4

40.

Question 40. For the reaction A + B → C + D, doubling the concentration ofboth the reactants increases the reaction rate by 8 times and doubling the concentration of only B simply doubles the reaction rate. The rate law is given as

(a) r = k[A]12 [B]12

(b) r = k [A] [B]²

(c) r – k [A]² [B]

(d) r = k [A] [B]

41.

Question 41. In Arrhenius plpt, intercept is equal to

(a) -Ea/R

(b) ln A

(c) ln k

(d) log10 a

42.

Question 42. What will be the fraction of molecules having energy equal to or greater than activation energy, Ea?

(a) K

(b) A

(c) Ae-Ea/Rt

(d) e-Ea/Rt

43.

Question 43. Chemistry MCQs for Class 12 with Answers Chapter 4 Chemical Kinetics 1 What type of reaction is this?

(a) Second order

(b) Unimolecular

(c) Pseudo-unimolecular

(d) Third order

44.

Question 44. Which among the following is a false statement?

(a) Rate of zero order reaction is independent of initial concentration of reactant.

(b) Half life of a third order reaction is inversely proportional to square of initial concentration of the reactant.

(c) Molecularity of a reaction may be zero or fraction.

(d) For a first order reaction, t1/2=0.693K

45.

Question 45. Which of the following statements about the catalyst is true?

(a) A catalyst accelerates the rate of reaction by bringing down the activation energy.

(b) A catalyst does not participate in reaction mechanism.

(c) A catalyst makes the reaction feasible by making ∆G more negative.

(d) A catalyst makes equilibrium constant more favourable for forward reaction.

46.

Question 46. Mechanism of a hypothetical reaction X2 + Y2 → 2 × Y is given below: Chemistry MCQs for Class 12 with Answers Chapter 4 Chemical Kinetics 2 (b) X + Y2 → XY + Y (slow) (c) X + Y → XY (fast) The overall order of reaction is

(a) 2

(b) 0

(c) 1.5

(d) 1

47.

Question 47. For the reaction N2 + 3H2 → 2NH3 if Δ[NH3]Δt = 2 × 10-4 mol L-1s-1, the value of −Δ[H2]Δt would be

(a) 1 × 10-4 mol L-1s-1

(b) 3 × 10-4 mol L-1s-1

(c) 4 × 10-4 mol L-1s-1

(d) 6 × 10-4 mol L-1s-1

48.

Question 48. The rate of a certain hypothetical reaction A + B + C → products is given by r = −d[A]dtK[A]1/2[B]1/3[C]1/4. The order of the reaction is

(a) 13/11

(b) 13/14

(c) 12/13

(d) 13/12

49.

Question 49. In the formation of S02 by contact process; 2SO2 + O2 → 2SO3, the rate of reaction was measured as −d[O2]dt = 2.5 × 10-4 mol L-1s-1. at The rate of formation of of S03 will be

(a) -5.0 × 10-4 mol L-1s-1

(b) -1.25 × 10-4 mol L-1s-1

(c) 3.75 × 10-4 mol L-1s-1

(d) 5.00 × 10-4 mol L-1s-1

50.

Question 50. For a chemical reaction A→B, it is found that the rate of reaction doubles when the concentration of A is increased four times. The order of reaction is

(a) Two

(b) One

(c) Half

(d) Zero

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