Chemical Kinetics PYQs Set 3 (PDF)

Set 3 of 8 · Questions 61-90 of 224

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Mere Teacher · Previous Year Questions NEET Chemistry · Chemical Kinetics · Set 3 (Q61-90)
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61. $For an elementary chemical reaction, A_{2} k_{1} ⇌ k_{- 1} 2 A, the expression for \frac{d ( A )}{dt} is :$ (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) $2 k_{1} (A_{2}) - 2 k_{- 1} (A)^{2}$ 62. $The slope of the graph drawn between ln k and \frac{1}{T} as per Arrhenius equation gives the value (R = gas constant, E_{α} = Activation energy)$ (1) $\frac{R}{E _{a}}$ (2) $\frac{E _{a}}{R}$ (3) $\frac{- E _{a}}{R}$ (4) $\frac{- R}{E _{a}}$ 63. $A first order reaction is 60 % complete in 20 minutes. How long will the reaction take to be 84 % complete?$ (1) $54 mins$ (2) $68 mins$ (3) $40 mins$ (4) $76 mins$ 64. $1 L of 2 M CH_{3} COOH is mixed with 1 L of 3 M C_{2} H_{5} OH to form an ester. The rate of the reaction with respect to the initial rate when each solution is diluted with an equal volume of water will be$ (1) $0.25 times$ (2) $2 times$ (3) $0.5 times$ (4) $4 times.$ 65. $In a first order reaction, the concentration of the reactant is reduced to 12.5 % in one hour. When was it half completed?$ (1) $20 min$ (2) $15 min$ (3) $3 hr$ (4) $30 min$ 66. $For a reaction, the value of rate constant at 300 K is 6.0 \times 10^{5} s^{- 1} . The value of Arrhenius factor A at infinitely high temperature is$ (1) $6 \times 10^{5} \times e^{- Ea /300 R}$ (2) $e^{- Ea /300 R}$ (3) $6\times 1 0^{- 5300}$ (4) $6 \times 10^{5}$ 67. $Which of the following statements is incorrect?$ (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) $Complex reactions have fractional order.$ 68. $The rate for reaction 2 A + B \to product is 6 \times 10^{- 4} mol dm^{- 3} s^{- 1} . Calculate the rate constant if the reaction is first order in A and zeroth order in B . [Given [A] = [B] = 0.3 M]$ (1) $1 \times 10^{- 3} s^{- 1}$ (2) $3 \times 10^{- 3} s^{- 1}$ (3) $2 \times 10^{- 3} s^{- 1}$ (4) $4 \times 10^{- 3} s^{- 1}$ 69. $For following reactions A \to A 500 K 700 K product A \to catalyst 500 K product it was found that the E_{a} is decreased by 30 mol in the presence of catalyst. If the rate remains unchanged, the activation energy for catalysed reaction is (Assumer pre exponential factor is same):$ (1) $75 k J$ (2) $135 kJ$ (3) $105 kJ$ (4) $125 kJ$ 70. $By the action of enzymes, the rate of biochemical reaction$ (1) $does not change$ (2) $increases$ (3) $decreases$ (4) $either (a) or (c).$ 71. $At 30°C, the half life for the decomposition of A B_{2} is 200 s and is independent of the initial concentration of A B_{2} . The time required for 80% of the A B_{2} to decompose is (Given: log 2 = 0.30; log 3 = 0.48)$ (1) $200s$ (2) $323s$ (3) $467 s$ (4) $532 s$ 72. $For a chemical reaction A + B \to Product, the order is 1 with respect to A and B. Rate [A] [B] mol L^{- 1} S^{- 1} mol L^{- 1} mol L^{- 1} 0.10 20 0.5 0.40 x 0.5 0.80 40 y What is the value of x and y?$ (1) $160 and 4$ (2) $80 and 4$ (3) $80 and 2$ (4) $40 and 4$ 73. $Integrated rate law equation for a first order gas phase reaction is given by (where P_{i} is initial pressure and P_{t} is total pressure at time t)$ (1) $k = \frac{2.303}{t} \times log \frac{P _{i}}{( 2 P _{i} - P _{t} )}$ (2) $k = \frac{2.303}{t} \times log \frac{2 P _{i}}{( 2 P _{i} - P _{t} )}$ (3) $k = \frac{2.303}{t} \times log \frac{( 2 P _{i} - P _{t} )}{P _{i}}$ (4) $k = \frac{2.303}{t} \times \frac{P _{i}}{( 2 P _{i} - P _{t} )}$ 74. $In which one of the following reactions, rate constant has the unit mol L^{- 1} s^{- 1} ?$ (1) $Acid catalysed hydrolysis of CH_{3} COOCH_{3}$ (2) $CHCl_{3} + Cl_{2} ⟶ CCl_{4} + HCl$ (3) $2 NO_{(g)} + O_{2 (g)} ⟶ 2 NO_{2 (g)}$ (4) $Decomposition of HI on the surface of gold$ 75. $A bacterial infection in an internal wound grows as N’ (t) = N_{0} exp (t), where the time t is in hours. A dose of antibiotic, taken orally, needs 1 hour to reach the wound. Once it reaches there, the bacterial population goes down as \frac{dN}{dt} = - 5 N^{2} . What will be the plot of \frac{N _{0}}{N} vs. t after 1 hour ?$ (1) (2) (3) (4) 76. $The half-life for a zero order reaction having 0.02 M initial concentration of reactant is 100 s . The rate constant (in mol L^{- 1} s^{- 1}) for the reaction is$ (1) $2.0 \times 10^{- 4}$ (2) $2.0 \times 10^{- 3}$ (3) $1.0 \times 10^{- 2}$ (4) $1.0 \times 10^{- 4}$ 77. $What is the value of rate constant for first order reaction if slope for the graph of rate versus concentration is 2.5 \times 10^{- 3} ?$ (1) $2.5 \times 10^{- 3} time^{- 1}$ (2) $5.0 \times 10^{- 3} time^{- 1}$ (3) $7.5 \times 10^{- 3} time^{- 1}$ (4) $1.25 \times 10^{- 3} time^{- 1}$ 78. $Decomposition of X exhibits a rate constant of 0.05 μg / year. How many years are required for the decomposition of 5 μg of X into 2.5 μg ?$ (1) $50$ (2) $25$ (3) $20$ (4) $40$ 79. $In a first order decomposition reaction, the time taken for the decomposition of reactant to one fourth and one eighth of its initial concentration are t_{1} and t_{2} (s), respectively. The ratio t_{1} / t_{2} will be:$ (1) $\frac{4}{3}$ (2) $\frac{3}{2}$ (3) $\frac{3}{4}$ (4) $\frac{2}{3}$ 80. $If the rate of the reaction is equal to the rate constant, the order of the reaction is$ (1) $0$ (2) $1$ (3) $2$ (4) $3$ 81. $Which of the following is a zero order reaction?$ (1) $2 HI \to H_{2} + I_{2}$ (2) $H_{2} + B r_{2} Δ 2 H B r$ (3) $2 N_{2} O_{5} \to 4 NO_{2} + O_{2}$ (4) $H_{2} + Cl_{2} \to hv 2 HCl$ 82. $In the first order thermal decomposition of C_{2} H_{5} I (g) \to C_{2} H_{4} (g) + HI (g), the reactant in the beginning exerts a pressure of 2 bar in a closed vessel at 600 K . If the partial perssure of the reactant is 0.1 bar after 1000 minutes at the same temperature the rate constant in min^{- 1} is (log 2 = 0.3010)$ (1) $6.0 \times 10^{- 4}$ (2) $6.0 \times 10^{- 3}$ (3) $3.0 \times 10^{- 3}$ (4) $3.0 \times 10^{- 4}$ 83. $Half life of zero order reaction A \to product is 1 hour, when initial concentration of reactant is 2.0 mol L^{- 1} . The time required to decrease concentration of A from 0.50 to 0.25 mol L^{- 1} is:$ (1) $0.5 hour$ (2) $15 min$ (3) $60 min$ (4) $4 hour$ 84. $If the equilibrium constant for A ⇌ B + C is K_{eq}^{(1)} and that of B + C ⇌ P is K_{eq}^{(2)} the equilibrium constant for A ⇌ P is$ (1) $K_{eq}^{(1)} / K_{eq}^{(2)}$ (2) $K_{eq}^{(1)} + K_{eq}^{(2)}$ (3) $K_{eq}^{(2)} - K_{eq}^{(1)}$ (4) $K_{eq}^{(1)} K_{eq}^{(2)}$ 85. $For the chemical reaction N_{2} (g) + 3 H_{2} (g) ⇌ 2 NH_{3} (g) The correct option is:$ (1) $- \frac{1}{3} \frac{d ( H _{2} )}{dt} = - \frac{1}{2} \frac{d ( NH _{3} )}{dt}$ (2) $- \frac{d ( N _{2} )}{dt} = 2 \frac{d ( NH _{3} )}{dt}$ (3) $- \frac{d ( N _{2} )}{dt} = \frac{1}{2} \frac{d ( NH _{3} )}{dt}$ (4) $3 \frac{d ( H _{2} )}{dt} = 2 \frac{d ( NH _{3} )}{dt}$ 86. $For the reaction 2 A + B \to C, the values of initial rate at different reactant concentration are given in the table below. The rate law for the reaction is : [A] (mol L^{- 1}) [B] (mol L^{- 1}) Initial Rate (mol L^{- 1} s^{- 1}) 0.05 0.05 0.045 0.10 0.05 0.090 0.20 0.10 0.72$ (1) $Rate = k (A) (B)^{2}$ (2) $Rate = k (A)^{2} (B)^{2}$ (3) $Rate = k (A) (B)$ (4) $Rate = k (A)^{2} (B)$ 87. $The first order decomposition of in an appropriate medium is characterised by a rate constant of 0.2303 . What is the time (in ) required to complete fraction of the reaction?$ (1) $0.1$ (2) $10$ (3) $100$ (4) $0.01$ 88. $The rate constant for a first order reaction is 4.606 \times 10^{- 3} s^{- 1} . The time required to reduce 2.0 g of the reactant to 0.2 g is:$ (1) $200 s$ (2) $500 s$ (3) $1000 s$ (4) $100 s$ 89. $For the reaction A + B \to C, the following data were obtained Exp Initial concentration Initial rate [A] M [B] M (M min^{- 1}) 1. 0.1 0.1 1.0 \times 10^{- 4} 2. 0.1 0.3 9.0 \times 10^{- 4} 3. 0.3 0.3 2.7 \times 10^{- 3} The order of reaction with respect to A and B are respectively$ (1) $1,2$ (2) $2,1$ (3) $1.5, 1.5$ (4) $0,3$ 90. $The rate of a certain biochemical reaction at physiological temperature (T) occurs 10^{6} times faster with enzyme than without. The change in the activation energy upon adding enzyme is:$ (1) $- 6 \times 2.303 RT$ (2) $+ 6 \times 2.303 RT$ (3) $+ 6 RT$ (4) $- 6 RT$