Chemical Kinetics PYQs Set 3 (PDF)

Set 3 of 11 · Questions 61-90 of 311

In the print window choose “Save as PDF”. The file prints without a web address or date line.

Mere Teacher · Previous Year Questions JEE Main Chemistry · Chemical Kinetics · Set 3 (Q61-90)
Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.
61. $Half life periods for a reaction at initial concentrations of 0.1 M and 0.01 M are 5 and 50 minutes, respectively. The order of reaction is$ (1) $3$ (2) $2$ (3) $1$ (4) $0$ 62. $For the elementary reaction, 2 SO_{2 (g)} + O_{2 (g)} \to 2 SO_{3 (l)}, identify the correct relation among the following.$ (1) $- \frac{d ( SO _{2 (g)} )}{dt} = - \frac{d ( O _{2 (g)} )}{dt}$ (2) $+ \frac{1}{2} \frac{d ( SO _{3 (g)} )}{dt} = + \frac{d ( SO _{2 (g)} )}{dt}$ (3) $+ \frac{d ( SO _{3 (g)} )}{dt} = - 2 \frac{d ( O _{2 (g)} )}{dt}$ (4) $+ \frac{d ( SO _{2 (g)} )}{dt} = - \frac{d ( O _{2 (g)} )}{dt}$ 63. $The half-life period of a first order reaction is 60 minutes. What percentage will be left over after 240 minutes?$ (1) $6.25 %$ (2) $4.25 %$ (3) $5 %$ (4) $6 %$ 64. $The time required for completion of 93.75 % of a first order reaction is x minutes. The half life of it (in minutes) is$ (1) $x /8$ (2) $x /2$ (3) $x /4$ (4) $x /3$ 65. $Consider an elementary reaction A (g) + B (g) \to C (g) + D (g) If the volume of reaction mixture is suddenly reduced to \frac{1}{3} of its initial volume, the reaction rate will become ' x' times of the original reaction rate. The value of x is:$ (1) $3$ (2) $\frac{1}{9}$ (3) $9$ (4) $\frac{1}{3}$ 66. $For the reaction O_{3 (g)} + O_{(g)} ⟶ 2 O_{2 (g)}, if the rate law expression is, rate = k (O_{3}) [O] the molecularity and order of the reaction are respectively$ (1) $2 and 2$ (2) $2 and 1.33$ (3) $2 and 1$ (4) $1 and 2$ 67. $For a first order reaction (A \to B), the temperature (T) dependent rate constant (k) in s^{- 1} was found to follow the equation : lo g k = - \frac{20}{T} + 4 . The activation energy (E_{a}) and preexponential factor (A) respectively, are$ (1) $46.06 c a l m o l^{- 1} and 1 0^{- 4} s^{- 1}$ (2) $92.12 c a l m o l^{- 1} and 1 0^{4} s^{- 1}$ (3) $46.06 c a l m o l^{- 1} and 1 0^{4} s^{- 1}$ (4) $9.212 c a l m o l^{- 1} and 1 0^{- 4} s^{- 1}$ 68. $What will be the overall order of a reaction for which the rate expression is given as Rate = k [A]^{\frac{1}{2}} [B]^{\frac{3}{2}}$ (1) $second order$ (2) $first order$ (3) $zero order$ (4) $third order$ 69. $In the chemical reaction A \to B, what is the order of the reaction? Given that, the rate of reaction doubles if the concentration of A is increased four times.$ (1) $2$ (2) $1.5$ (3) $0.5$ (4) $1$ 70. $A flask contains a mixture of compounds A and B. Both compounds decompose by first-order kinetics. The half-lives for A and B are 300 s and 180 s, respectively. If the concentrations of A and B are equal initially, the time required for the concentration of A to be four times that of B (in s) is : (Use 2 = 0.693)$ (1) $120$ (2) $300$ (3) $180$ (4) $900$ 71. $The rate law for the reaction A + B \to product is rate = k [A] [B] . When will the rate of reaction increase by factor two?$ (1) $[A] and [B] both are doubled$ (2) $[A] is doubled and [B] is kept constant$ (3) $[B] is doubled and [A] is halved$ (4) $[A] is kept constant and [B] is halved$ 72. $The slope of Arrhenius Plot (ln Kv / s 1/ T) of first order reaction is - 5 \times 10^{3} K . The value of E_{a} of the reaction is. Choose the correct option for your answer. [Given R = 8.314 JK^{- 1} mol^{- 1}]$ (1) $83.0 kJ mol^{- 1}$ (2) $166 kJ mol^{- 1}$ (3) $- 83 kJ mol^{- 1}$ (4) $41.5 kJ mol^{- 1}$ 73. $Half-life period of a first order reaction, A \to product is 6.93 hour. What is the value of rate constant?$ (1) $1.596 h^{- 1}$ (2) $4.802 h^{- 1}$ (3) $0.1 h^{- 1}$ (4) $10 h^{- 1}$ 74. $Por a chemical reaction, rate law is, rate = k [A]^{2} [B] . If [A] is doubled at constant [B], the rate of reaction$ (1) $increases by a factor of 8$ (2) $increase by a factor of 4$ (3) $increases by a factor of 3$ (4) $increase by a factor of 2 .$ 75. $At 27^{\circ} C in presence of a catalyst, activation energy of a reaction is lowered by 10 kJ mol^{- 1} . The logarithm of ratio of \frac{k ( catalysed )}{k ( uncatalysed )} is.... (Consider that the frequency factor for both the reactions is same)$ (1) $1.741$ (2) $17.41$ (3) $3.482$ (4) $0.1741$ 76. $For an elementary chemical reaction, A_{2} k_{1} ⇌ k_{- 1} 2 A, the expression for \frac{d ( A )}{dt} is :$ (1) $k_{1} (A_{2}) - k_{- 1} (A)^{2}$ (2) $2 k_{1} (A_{2}) - k_{- 1} (A)^{2}$ (3) $k_{1} (A)^{2} + k_{- 1} (A)^{2}$ (4) $2 k_{1} (A_{2}) - 2 k_{- 1} (A)^{2}$ 77. $The slope of the graph drawn between ln k and \frac{1}{T} as per Arrhenius equation gives the value (R = gas constant, E_{α} = Activation energy)$ (1) $\frac{R}{E _{a}}$ (2) $\frac{E _{a}}{R}$ (3) $\frac{- E _{a}}{R}$ (4) $\frac{- R}{E _{a}}$ 78. $A first order reaction is 60 % complete in 20 minutes. How long will the reaction take to be 84 % complete?$ (1) $54 mins$ (2) $68 mins$ (3) $40 mins$ (4) $76 mins$ 79. $1 L of 2 M CH_{3} COOH is mixed with 1 L of 3 M C_{2} H_{5} OH to form an ester. The rate of the reaction with respect to the initial rate when each solution is diluted with an equal volume of water will be$ (1) $0.25 times$ (2) $2 times$ (3) $0.5 times$ (4) $4 times.$ 80. $In a first order reaction, the concentration of the reactant is reduced to 12.5 % in one hour. When was it half completed?$ (1) $20 min$ (2) $15 min$ (3) $3 hr$ (4) $30 min$ 81. $For a reaction, the value of rate constant at 300 K is 6.0 \times 10^{5} s^{- 1} . The value of Arrhenius factor A at infinitely high temperature is$ (1) $6 \times 10^{5} \times e^{- Ea /300 R}$ (2) $e^{- Ea /300 R}$ (3) $6\times 1 0^{- 5300}$ (4) $6 \times 10^{5}$ 82. $Which of the following statements is incorrect?$ (1) $Molecularity is only applicable for elementary reaction.$ (2) $The rate law for any reaction cannot be determined experimentally.$ (3) $Biomolecular reactions involve simultaneous collision between two species.$ (4) $Complex reactions have fractional order.$ 83. $The rate for reaction 2 A + B \to product is 6 \times 10^{- 4} mol dm^{- 3} s^{- 1} . Calculate the rate constant if the reaction is first order in A and zeroth order in B . [Given [A] = [B] = 0.3 M]$ (1) $1 \times 10^{- 3} s^{- 1}$ (2) $3 \times 10^{- 3} s^{- 1}$ (3) $2 \times 10^{- 3} s^{- 1}$ (4) $4 \times 10^{- 3} s^{- 1}$ 84. $For following reactions A \to A 500 K 700 K product A \to catalyst 500 K product it was found that the E_{a} is decreased by 30 mol in the presence of catalyst. If the rate remains unchanged, the activation energy for catalysed reaction is (Assumer pre exponential factor is same):$ (1) $75 k J$ (2) $135 kJ$ (3) $105 kJ$ (4) $125 kJ$ 85. $By the action of enzymes, the rate of biochemical reaction$ (1) $does not change$ (2) $increases$ (3) $decreases$ (4) $either (a) or (c).$ 86. $At 30°C, the half life for the decomposition of A B_{2} is 200 s and is independent of the initial concentration of A B_{2} . The time required for 80% of the A B_{2} to decompose is (Given: log 2 = 0.30; log 3 = 0.48)$ (1) $200s$ (2) $323s$ (3) $467 s$ (4) $532 s$ 87. $For a chemical reaction A + B \to Product, the order is 1 with respect to A and B. Rate [A] [B] mol L^{- 1} S^{- 1} mol L^{- 1} mol L^{- 1} 0.10 20 0.5 0.40 x 0.5 0.80 40 y What is the value of x and y?$ (1) $160 and 4$ (2) $80 and 4$ (3) $80 and 2$ (4) $40 and 4$ 88. $A and B decompose via first order kinetics with half-lives 54.0 and 18.0 min respectively. Starting froman equimolarnon reactive mixture of A and B, the time taken for the concentration of A to become 16 timesthat of is ___ min. (Round off to the Nearest Integer).$ 89. $The half-life of radioisotopic bromine - 82 is 36 hours. The fraction which remains after one day is_______ . (Given antilog$ 90. $For the first order reaction A \to B Br the half life is 30 mm. The time taken for 75% completion of the reaction is_____mm. (Nearest mteger) Given; log 2 = 0.3010 l_{O} g 3 = 0.4771 log 5 = 0.6989$