Chemical Kinetics MHT-CET PYQ's

MHT-CET 2008

1 . After how many seconds will the concentration of the reactant in a first order reaction be halved if the rate constant is 1.155 x 10^-3 s^-1

(A) 600
(B) 100
(C) 60
(D) 10

MHT-CET 2009

2. Which is a correct integrated rate equation?

(A) k = -2.303/t log a/(a - x)
(B) k = -2.303/t log (a - x)/a
(C) -d (a - x) = k dt
(D) All are integrated rate equations

3. For which order reaction, the unit of rate constant is time^-1 ?

(A) Zero order
(B) First order
(C) Second order
(D)Third order

MHT-CET 2010

4. The units of rate constant for first order reaction are

(A) mol L^-1 s^-1
(B) s^-1
(C) L mol^-1 s^-1
(D) L² mol^-2 s^-1

5. The first order integrated rate equation is

(A) k = x/t
(B) k = -2.303/t log a/(a-x)
(C) k = 1/t ln a/(a-x)
(D) k = 1/t x/a(a-x)

MHT-CET 2011

6. In a multistep reaction, the overall rate of reaction is equal to the

(A) rate of slowest step
(B) rate of fastest step
(C) average rate of various steps
(D) the rate of last step

7. 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 mo1^-1 K^-1

(A) 342 kJ mo1^-1
(B) 269 kJ mol^-1
(C) 34.7 kJ mol^-1
(D) 15.1 kJ mol^-1

MHT-CET 2014

8. Rate law for the reaction A + B → product is rate = k [A]² [B]. What is the rate constant if the rate of reaction at a given temperature is 0.22 Ms^-1. when [A] = 1M and [B] = 0.25 M?

(A) 3.52 M^-2s^-1
(B) 0.88 M^-2s^-1
(C) 1.136 M^-2s^-1
(D) 0.05 M^-2s^-1

MHT-CET 2015

9. For the reaction O₃(g) + O(g) → 2O₂(g) if the rate law expression is, rate = k [O₃] [O] the molecularity and order of the reaction are respectively

(A) 2 and 2
(B) 2 and 1.33
(C) 2 and 1
(D) 1 and 2

10. The relationship between rate constant and half-life period of zero order reaction is given by

(A) t_1/2 = [A]₀2kt
(B) t_1/2 = 0.693/k
(C) t_{1/2 =} [A]₀/2k
(D) t_1/2 = 2[A]₀/k

11. Half-life period of a first order reaction. A → product is 6.93 hour. What is the value of rate constant?

(A) 1.596 h^-1
(B) 0.1 h^-1
(C) 4.802 h^-1
(D) 10 h^-1

^{MHT-CET 2016}

12. The reaction takes place in two steps as

i) NO²C^(g) → NO²^(g) + Cl^(g) ii) NO²Cl^(g) + Cl^(g) → NO²^(g) + C1²^(g) Identify the reaction intermediate.

(A)NO²Cl^(g)
(B) NO²^(g)
(C) Cl²^(g)
(D) Cl^(g)

13. The rate constant and half-life of a first order reaction are related to each other as

(A) t_1/2 = 0.693/k
(B) t_1/2 = 0.693 k
(C) k = 0.693 t_1/2
(D) kt_1/2 = 1/0.693

14. Average rate of reaction 2 SO₂_(g) + O₂_(g) → 2SO₃_(g) is written as

(A) △[SO₂]/△t
(B) -△[O₂]/△t
(C) 1/2△[SO₂]/△t
(D) △[SO₃]/△t

MHT-CET 2017

15. Which among the following reactions is an example of pseudo first order reaction?

(A) Inversion of cane sugar
(B) Decomposition of H₂O₂
(C) Conversion of cyclopropane to propene
(D) Decomposition of N₂O₅

16. Which among the following equations represents Arrhenius equation?

(A) k = A.e^E_a/RT
(B) k = A.e^RT/E_a
(C) k = A/e^E_a/RT
(D) k = A/e^RT/E_a

17. The rate constant for a first order reaction 7.0 x 10^-4 s^-1. If initial concentration of reactant is 0.080, what is the half-life of reaction?

(A) 990 s
(B) 79.2 s
(C) 12375 s
(D) 10.10 x 10^-4

MHT-CET 2018

18. A certain reaction occurs in two steps as

i) 2SO2(g) + 2NO2(g) → 2SO3(g) + 2NO(g) ii) 2NO(g) + O2(g) → 2NO2(g)

in the reaction,

(A) NO2(g) is intermediate
(B) NO(g) is intermediate
(C) NO(g) is catalyst
(D) O2(g) is intermediate

19. Slope of the straight line obtained by plotting log₁₀k against 1/T represents what term?

(A) -E_a
(B) -2.303 E_a/R
(C) -E_a/2.303 R
(D) -E_a/R

MHT-CET 2019

20. For the elementary reaction 2SO₂_(g) + O₂_(g) → 2SO₃_(g), identify the correct among the following relations:

(A) +d[SO₃_(g)]/dt = -2d[O₂_(g)]/dt
(B) +d[SO₂_(g)]/dt = -d[O₂_(g)]/dt
(C) +1/2d[SO₃_(g)]/dt = d[SO₂_(g)]/dt
(D) -d[SO₂_(g)]/dt = -d[O₂_(g)]/dt

21. Which among the following reaction is an example of a zero order reaction?

(A) 2NH₃ → N₂_(g) + 3H₂
(B) C₁₂H₂₂O₁₁_(aq.) + H₂O_(l) → C₆H₁₂O₆_(aq.) + C₆H₁₂O₆_(aq.)
(C) H₂_(g) + I₂_(g) → 2HI_(g)
(D) 2H₂O₂_(l) → 2H₂_(l) + O₂_(g)

22. The activation energy of a reaction is zero. Its rate constant at 280 K is 1.6 x 10^-6 s^-1, the rate constant at 300 K is

(A) 1.6 x 10^-6 s^-1
(B) 1.6 x 10^-5 s^-1
(C) 3.2 x 10^-6 s^-1
(D) Zero

23. For a chemical reaction rate law is. rate = k [A]² [B]. If [A] is doubled at constant [B], the rate of reaction

(A) increases by a factor of 4
(B) increases by a factor of 3
(C) increases by a factor of 8
(D) increases by a factor of 2

24. For the elementary reaction, 3 H₂_(g) + N₂_(g) → 2NH₃_(g), identify the correct relation among the following relations.

(A) -3/2d[H2(g)]/dt = d[NH3(g)]/dt
(B) d[NH3(g)]/dt = -1/3 d[H2(g)]/dt
(C) -2/3d[H2(g)]/dt = d[NH3(g)]/dt
(D) -[H2(g)]/dt = d[NH3(g)]/dt

25. The integrated rate equation for first order reaction, A → Product, is

(A) k = 2.303 t log₁₀[A]_{0_{/[A]_t}}

(B) k = –1/t ln[A]_t/[A]₀

(D) k = 1/t ln[A]_t/[A]₀

26. Order of which among the following reactions is NOT one?

(A) 2H2O2(l) → 2H2O(l) + O2(g)
(B) Cyclopropane → CH3 -- CH == CH2(g)
(C) 2N2O5(g) → 2NO2(g) + O2(g)
(D) CHCl3(g) + Cl2(g) → CCl4(g) + HCl(g)

27. Consider the reaction 2A + B → product. When conc. of 'B' alone was doubled, the half-life, is not change. When conc. of 'A' alone was doubled, the rate increases by two times, order of of reaction is

(A) 2
(B) 1.5
(C) 1
(D) 0

28. Consider the reaction 2A + 2B → C + 2D, if concentration of A is doubled at constant [B], rate increases by a factor 4. If concentration B is doubled at constant [A] the rate is doubled. Rate law of the reaction is

(A) rate = k[A]2 [B]
(B) rate = k[A] [B]2
(C) rate = k[A]2 [B]2
(D) rate = k[A] [B]

29. If the half-life period of a first order reaction is 200 minutes, the rate constant will be

(A) 9.605 x 10^-2 min^-1
(B) 3.465 x 10^-3 min^-1
(C) 1.374 x 10^-3 min^-1
(D) 288.6 min^-1

30. If the rate of reaction is expressed as, -1/3d[A]/dt = -1/2d[B]/dt = d[C]/dt, the reaction is

(A) 3A + 2B → C
(B) 2B → 3A + C
(C) 2B + C → 3A
(D) 3A → 2B + C

31. A → B is first order reaction with rate equal to 6.6 x 10^-5 M s^-1. When [A] is 0.6 M, rate constant of the reaction is

(A) 9 x 10^-5 s^-1
(B) 9 x 10^-4 s^-1
(C) 1.1 x 10^-4 s^-1
(D) 1.1 x 10^-5 s^-1

MHT-CET 2020

32. Which of the following is a character of catalyst?

(A) It increases the rates of both forward and backward reactions equally in reversible reaction
(B) It increases the activation energy of reactants
(C) It affects the energies of reactants and products of the reaction
(D) It changes the position of equilibrium

33. In the reaction. N2 is + 3H2 → 2NH3, the rate of disappearance of H2 is 0.02 M/s. The rate of appearance of NH3 is

(A) 0.0133 M/s
(B) 0.004 M/s
(C) 0.032 M/s
(D) 0.023

34. Which among the following is correct when energy of activation, Ea of the catalyzed reaction decreases at constant temperature and for same concentration?

(A) e^-Ea/RTdecreases
(B) -Ea/RT decreases
(C) K decreases
(D) Ea/RT decreaces

35. Half-life of first order reaction is 20 minutes. What is the time taken to reduce the initial concentration of the reactant to 1/10 th ?

(A) 66.56 min
(B) 6.6 min
(C) 150 min
(D) 79.68 min

36. The rate law for the reaction 2NO(g) + O2(g) → 2NO2(g) is rate = k[NO]²[O2], then which

among the following is correct?

(A) The reaction is first order in O2, first order in NO and second order overall
(B) The reaction is second order in NO, zero order in O2 and second order overall
(C) The reaction is second order in NO, first order in O2 and third order overall
(D) The reaction is zero order overall

37. In a first order reaction 87.5% of reactant is converted into product in 15 minutes. The rate constant for the reaction is given by

(A) 5/0.693 min^-1
(B) 0.693/15 min^-1
(C) 0.693 x 5 min^-1
(D) 0.693/5 min^-1

38. The half-life of a first order reaction is 6.0 hour. How long will it take for the concentration of reactant to decrease from 0.4 M to 0.12 M?

(A) 10.42 h
(B) 9.51 h
(C) 30.36 h
(D) 4.25 h

39. For the first order reaction A → B, the rate constant is 0.25 s^-1, if the concentration of A is reduced to half, the value of rate constant will be

(A) 0.25 s^-1
(B) 0.30 s^-1
(C) 2.25 s^-1
(D) 0.075 s^-1

40. For the reaction 4NH3 + 5O2 → 4NO + 6H2O, the rate of disappearance of NH3 is 3.6 x 10^-3M/s. What is the rate of formation of water?

(A) 6.0 x 10^-4 M/s
(B) 5.4 x 10^-3 M/s
(C) 3.6 x 10^-3 M/s
(D) 4.0 x 10^4 M/s

41. The rate law for the reaction A + B + C → Product is expressed as Rate = k[A]² [B]1 [C]0. What is the overall order of the reaction?

(A) 3
(B) 1
(C) 2
(D) 0

42. The reaction N205 → 2NO2 + 1/2O2 is first order in N205 having rate constant 6.2 x 10^-4 s^-1. What is the value of rate of reaction when concentration of N2O5 is 1.25 mol L^-1?

(A) 7.75 x 10^-4 mol L^-1 s^-1
(B) 8.15 x 10^-4 mol L^-1 s^-1
(C) 4.96 x 10^-4 mol L^-1 s^-1
(D) 2.01 x 10^-4 mol L^-1 s^-1

43. The rate constant for first order reaction is 0.02232 min^-1. Calculate the time required for 75% completion of the reaction.

(A) 62.12 min
(B) 38.31 min
(C) 48.12 min
(D) 12.77 min

44. Which among the following is an example of zero order reaction?

(A) Hydrolysis of CH3COOCH3
(B) inversion of C12H22O11
(C) Decomposition of N2O in presence of catalyst
(D) Decomposition of N2O5

45. What is the unit of rate constant for the zero order reaction?

(A) t^-1
(B) mol dm³ t^-1
(C) mol dm^-3 t^-1
(D) mol dm^-3 t

46. For first order reaction the slope of the graph of log[A]t Vs. time is equal to

(A) k
(B) -k
(C) -k/2.303
(D) k/2.303

47. What is the order of reaction for decomposition of gaseous acetaldehyde?

(A) 0
(B) 2
(C) 1.5
(D) 1

48. If concentration of reactant 'A' is increased by 10 times, the rate of reaction becomes 100 times. What is the order of reaction if rate law is, rate = k[A]x

(A) 2
(B) 1
(C) 3
(D) 4

49. A first order reaction has rate constant 1 x 10^-2 s^-1. What time will it take for 20 g of reactant to reduce to 5 g?

(A) 138.6 s
(B) 238.6 s
(C) 693.0 s
(D) 346.5 s

50. What is the value of rate constant of first order reaction, if it takes 15 minutes for consumption of 20% of reactants?

(A) 1.07 x 10^-2 min^-1
(B) 1.48 x 10^-2 min^-1
(C) 1.84 x 10^-2 min^-1
(D) 1.38 x 10^-2 min^-1

51. A first order reaction has a rate constant 0.00813 min^-1, how long will it take for 60% completion?

(A)112.7 min
(B) 56.35 min
(C) 62.77 min
(D) 98.7 min

52. Half-life of first order reaction X → Y + Z is 3 minutes. What is the time required to reduce the concentration of 'X' by 90 % of it's initial concentration?

(A) 9.969 minutes
(B) 4.12 minutes
(C) 9.105 minutes
(D) 12.05 minutes

53. A first order reaction is 25% completed in 40 minutes. What is the rate constant k for reaction?

(A) 2.303/40 x log1/4
(B) (2.303 x log 1.33)/40
(C) (2.303 x log 4)/120
(D) 2.303 x log 4/3

54. For first order reaction the concentration of reactant decreases form 0.2 to 0.1 M in 100 minutes What is the rate constant of the reaction?

(A) 144.3 min^-1
(B) 6.93 min^-1
(C) 69.3 min^-1
(D) 6.93 x 10^-3 min^-1

55. A first order reaction is 75% completed in 60 minutes, the time required for it's 50% completion is

(A) 30 min
(B) 60 min
(C) 120 min
(D) 40 min

56. What is the molecularity and order of the following reaction if rate law is, rate = k[O3][O] respectively?

O3(g) + O(g) → 2O2(g)

(A) 3 and 1
(B) 3 and 2
(C) 4 and 2
(D) 2 and 2

57. For a first order reaction, A → B, if [A] = 1 M and rate is 4 x 10^-2 M s^-1. What is the rate constant of the reaction?

(A) 4 x 10^-2 s^-1
(B) 0.4 x 10^-2 s^-1
(C) 2 x 10^-2 s^-1
(D) 2.5 x 10^-5 s^-1

58. For the reaction, 2NOBr(g) → 2NO(g) + Br2(g), rate law is r = k [NOBr]².

If rate constant is 1.62 Ms^-1 and concentration of NOBr is 2.00 x 10^-3M, what is the rate of reaction?

(A) 2.46 x 10^-6 Ms^-1
(B) 5.24 x 10^-6 Ms^-1
(C) 6.48 x 10^-6 Ms^-1
(D) 4.05 x 10^-5 Ms^-1

59. In the reaction 2SO2 + O2 → 2SO3 the rate of appearance of SO3 is 4 x 10^-4 M/s, the rate of disappearance of O2 is

(A) 1.0 x 10^-4 M/s
(B) 4.0 x 10-4 M/s
(C) 2.0 x 10^-4
(D) 6.0 x 10^-4 M/s

60. Which among the following is an example of pseudo first order reaction?

(A) 2N2O5(g) → 4NO2(g) + O2(g)
(B) CH2 --CH2-- CH2 → CH3 -- CH= CH2
(C) H2O2(l) → 2H2)(l) + O2(g)
(D) CH3COOCH3(aq.) + H2O → CH3COOH(aq.) + CH3OH(aq.)

61. Which is the average rate of reaction when the change in concentration of product is 0.05 M in 20 seconds?

(A) 4.0 m/s
(B) 0.05 M/s
(C) 0.0025 M/s
(D) 1.0 M/s

62. In the reaction A + B2 → AB + B, the rate of reaction is direct, proportional to the cocentration of A and independent on the concentration of B2. What is the rate law expression?

(A) rate = k[A]
(B) rate = k[B2]
(C) rate = k[A][B2]
(D) rate = K[A]²[B2]

63. The rate for the reaction is r1 = k[A][B]. If the concentration of A is doubled and that of B is halved, the new rate is r2 then what is the ratio of r2/r1?

(A) 2^( a – b)
(B) a - b
(C) a + b
(D) 1/2^(a+b)

64. The reaction 2NO2Cl(g) → 2NO2(g) + Cl2(g) takes place in two steps its

(i) NO2Cl(g) → 2NO2(g) + Cl2(g)

(ii) NO2Cl(g) + Cl(g) → NO2(g) + Cl2(g)

Identify the reaction intermediate.

(A) NO2(g)
(B) NO2Cl(g)
(C) Cl(g)
(D) C12(g)

65.1n the reaction 2SO2(g) + O2(g) → 2SO3(g), the rate of disappearance of SO2 is 1.28 x 10^-5 M/s. What is the rate of appearance of SO3?

(A) 2.56 x 10^-5 M/s
(B) 1.25 x 10^-5 M/s
(C) 0.64 x 10^-5 M/s
(D) 0.32 x 10^-5 M/s

66. A first order reaction takes 40 minutes for 30% decomposition. What is the half-life of reaction?

(A) 59.5 min
(B) 77.8 min
(C) 67.8 min
(D) 82.2 min

67. A certain zero order reaction is 50% completed in 10 minutes. What percentage does the reaction completes after 15 minutes?

(A) 65%
(B) 25%
(C) 75%
(D) 60%

68. In a reaction N2(g) + 3H2(g) → 2NH3(g), if the rate of disappearance of N2(g) is 2.6 x 10^-4 M/s, the rate of disappearance of H2(g) in M/s is

(A) 8.6 x 10^-4 M/s
(B) 5.2 x 10^-4 M/s
(C) 2.6 x 10^-4 M/s
(D) 7.8 x 10-4 M/s

69. Which is the unit of rate constant for the first order reaction if time is expressed in seconds?

(A) mol^-1 dm³ s^-1
(B) s^-1
(C) mol dm^-3 s^-1
(D) mol dm^-3 s

70. Reaction given below follows first order kinetics: 2 N2O2 → 4NO2 + O2

Calculate rate constant of reaction if concentration of N2O2 is 0.05 M and rate of reaction is

1.5 x 10^-6 mol L^-1 s^-1

(A) 2.5 x 10^-5 s^-1
(B) 3.0 x 10^-5 s^-1
(C) 1.5 x 10^-5 s^-1
(D) 2.0 x 10^-5 s^-1

71. A certain zero order reaction has rate constant 0.025 M s^-1. What will be the concentration of reactant 'A' after 15 seconds, if initial concentration is 0.50 M?

(A) 0.50 M
(B) 0.125 M
(C) 0.375 M
(D) 0.060 M

72. The reaction A + B → P, is second order in A and first order in B. What is the rate law for the reaction?

(A) Rate = k[A] [B]
(B) Rate = k[A]² [B]^1/2
(C) Rate = k[A]² [B]
(D) Rate = k[A] [B]²

73. A first order reaction is 50 % completed in 50 minutes. What is the rate constant of the reaction?

(A) 7.215 x 10^-1 min^-1
(B) 3.465 x 10^-2 min^-1
(C) 1.386 x 10^-2 min^-1
(D) 1.386 x 10^-1 min^-1

74. A first order reaction takes 40 minutes for 30% completion. Calculate the half-life of reaction

(A) 77.7 min
(B) 23.1 min
(C) 42.7 min
(D) 57.8 min

75. Rate constant for zero order reaction is 2 x 10^-2 mol^-1 s^-1. If the concentration of the reactant after 25 sec. is 0.5 M, what is the initial concentration of reactant?

(A) 0.125 M
(B) 0.5 M
(C) 1.25 M
(D) 1.0 M

76. The slope of a graph. log [A]t versus 't' for a first order reaction is - 2.5 x 10^-3 s^-1. The rate constant for the reaction is

(A) - 2.5 x 10^-3 s^-1
(B) 2.5 x 10^-3 s^-1
(C) 1.086 x 10^-3 s^-1
(D) 5.757 x 10^-3 s^-1

77(78). A first order reaction, A → B takes 100 minutes for it's 90% completion. What is the rate constant of reaction?

(A) 0.0460 min^-1
(B) 0.0230 min^-1
(D) 0.2303 min^-1
(D) 0.4606 min^-1

78. 0.0210 M solution of N2O5 is allowed to decompose at 43°C. How long will it take to reduce 0.0150M ? (Given k = 6.0 x 10^-4 sec^-1)

(A) 3364 sec
(B) 360.0 sec
(C) 560.0 sec
(D) 5600 sec

79. The rate of first order reaction A → B is 6.3 x 10^-6 M s^-1, if [A] = 0.3 M, what is the rate constant of the reaction?

(A) 1.3 x 10^-5 s^-1
(B) 2.1 x 10^-5 s^-1
(C) 1.2 x 10^-5 s^-1
(D) 1.6 x 10^-5 s^-1

80. For zero order reaction, when [A]t is plotted against time (t), the slope of the straight line obtained is equal to

(A) -k
(B) -kt
(C) k
(D) [A]0

81. A first order reaction is 50 % completed in 16 minutes. The percentage of reactant that will react in 32 minutes is

(A) 75 %
(B) 12-5%
(C) 25%
(D) 100%

82. Consider the reaction; 2N2O5(g) → 4NO2(g) + O2(g). What is the rate of reaction, when the concentration of NO2 increases to 5.2 x 10^-3 M in 100 sec?

(A) 2 x 10^-5 M/s
(B) 7.6 x 10^-4 M/s
(C) 5 x 10^-4 M/s
(D) 1.3 x 10^-5 M/s

83. For the reaction 2A + B → 3C + D, which among the following is NOT the correct rate law expression ?

(A) -d[A]/2dt
(B) -d[B]/dt
(C) d[D]/dt
(D) -d[C]/3dt

84. The time required to decompose SO₂Cl₂ to half of it's initial amount is 60 minutes. Calculate rate constant for the first order reaction.

(A) 4.158 x 10^-2 min^-1
(B) 2.651 x 10^-2 min^-1
(C) 1.155 x 10^-2 min^-1
(D) 1.551 x 10^-2 min^-1

85. The rate constant for the first order reaction is 1.15 x 10^-3 s^-1. How long will 5g of the reactant take to reduce to 3g?

(A) 414 sec
(B) 444 sec
(C) 424 sec
(D) 434 sec

86. When the temperature of first order reaction increases then according to Arrhenius equation which among the following is correct?

(A) e - Ea/RT decreases
(B) Ea/RT increases
(C) -Ea/RT decreases
(D) k decreases

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