Chemical Kinetics PYQs Set 5 (PDF)

Set 5 of 11 · Questions 121-150 of 311

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Chemical Kinetics · Set 5 (Q121-150)
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121. $Which among the following reactions is an example of pseudo-first order reaction?$ (1) $Inversion of cane sugar$ (2) $Decomposition of H_{2} O_{2}$ (3) $Conversion of cyclopropane to propene$ (4) $Decomposition of N_{2} O_{5}$ 122. $For n^{th} order of reaction, half-life period is directly proportional to$ (1) $a^{n - 1}$ (2) $a^{1 - n}$ (3) $none of the above$ (4) $1 a^{1 - n}$ 123. $The activation energy for a reaction at the temperature T K was found to be 2.303 RT J mol^{- 1} . The ratio of the rate constant to Arrhenius factor is$ (1) $10^{- 1}$ (2) $10^{- 2}$ (3) $2 \times 10^{- 3}$ (4) $2\times 1 0^{- 2}$ 124. $The activation energy of a chemical reaction can be determined by$ (1) $evaluating rate constants at two different temperatures$ (2) $changing the concentration of reactants$ (3) $evaluating the concentration of reactants at two different temperatures$ (4) $evaluating rate constant at standard temperature.$ 125. $The rate constants k_{1} and k_{2} for two different reactions are 10^{16} \times e^{- 2000/ T} and 10^{15} \times e^{- 1000/ T} respectively. The temperature at which k_{1} = k_{2} is$ (1) $\frac{2000}{2.303} K$ (2) $2000 K$ (3) $\frac{1000}{2.303} K$ (4) $1000 K$ 126. $Find the correct equation among the following.$ (1) $ln k - ln A = \frac{E _{a}}{RT}$ (2) $k = \frac{A E _{a}}{RT}$ (3) $ln k + ln A = \frac{E _{a}}{RT}$ (4) $\frac{E _{a}}{RT} = ln A - ln k$ 127. $If the rate constant for a first order reaction is 2.303 \times 10^{- 3} s^{- 1} . Find the time required to reduce 4 g of the reactant to 0.2 g .$ (1) $1.30 hours$ (2) $21.60 hours$ (3) $0.36 hours$ (4) $2.60 hours$ 128. $Time required for 100 percent completion of a zero order reaction is$ (1) $\frac{2 k}{a}$ (2) $\frac{a}{2 k}$ (3) $\frac{a}{k}$ (4) $ak$ 129. $A_{(g)} \to Δ P_{(g)} + Q_{(g)} + R_{(g)}, follows first order kinetics with a half-life of 69.3 s at 500^{\circ} C . Starting from the gas ' A' enclosed in a container at 500^{\circ} C and at a pressure of 0.4 atm, the total pressure of the system after 230 s will be$ (1) $1.15 atm$ (2) $1.32 atm$ (3) $1.22 atm$ (4) $1.12 atm$ 130. $A (g) \to B (g) + C (g) is a first order reaction. Time t \infty P_{system} P_{t} P_{\infty} The reaction was started with reactant A only. Which of the following expressions is correct for rate constant k ?$ (1) $k = \frac{1}{t} ln \frac{p _{\infty}}{p _{t}}$ (2) $k = \frac{1}{t} ln \frac{p _{\infty}}{2 ( p _{\infty} - p _{t} )}$ (3) $k = \frac{1}{t} ln \frac{2 ( p _{\infty} - p _{t} )}{p _{t}}$ (4) $k = \frac{1}{t} ln \frac{p _{\infty}}{( p _{\infty} - p _{t} )}$ 131. $If 50 % of the reactant is converted into a product in a first order reaction in 25 minutes, how much of it would react in 100 minutes?$ (1) $93.75 %$ (2) $87.5 %$ (3) $75 %$ (4) $100 %$ 132. $The rate constant for a first order reaction is 7.0 \times 10^{- 4} s^{- 1} . If initial concentration of reactant is 0.080 M, what is the half life of reaction?$ (1) $990 s$ (2) $79.2 s$ (3) $12375 s$ (4) $10.10 \times 10^{- 4} s$ 133. $For a zero-order reaction, the correct expression for rate constant (k) at half-life time (t_{1/2}) is (R_{0} =) initial concentration of reactant)$ (1) $k = \frac{2.303}{t _{1/2}} log \frac{( R _{0} )}{\frac{( R _{0} )}{2}}$ (2) $k = \frac{2.303}{t} log \frac{( R _{0} )}{( R _{0} )}$ (3) $k = \frac{( R _{0} ) - \frac{1}{2} ( R _{0} )}{t _{1/2}}$ (4) $k = \frac{2.303}{( t _{2} - t _{1} )} log (R_{0})$ 134. $Drug X becomes ineffective after 50 % decomposition. The original concentration of drug in a bottle was 16 mg / mL which becomes 4 mg / mL in 12 months. The expiry time of the drug in months is Assume that the decomposition of the drug follows first order kinetics.$ (1) $2$ (2) $6$ (3) $12$ (4) $3$ 135. $The rate of reaction increases with rise in temperature because of$ (1) $increase in number of activated molecules$ (2) $increase in energy of activation$ (3) $decrease in energy of activation$ (4) $none of the above$ 136. $The concentration of a reactant X decreases from 0.1 M to 0.005 M in 40 minutes. If the reaction follows I order kinetics, the rate of the reaction when the concentration of X is 0.01 M will be$ (1) $1.73 \times 10^{- 4} M min^{- 1}$ (2) $3.47 \times 10^{- 4} M min^{- 1}$ (3) $3.47 \times 10^{- 5} M min^{- 1}$ (4) $7.5 \times 10^{- 4} M min^{- 1}$ 137. $A given sample of milk turns sour at room temperature (27^{\circ} C) in 5 hours. In a refrigerator at - 3^{\circ} C, it can be stored 10 times longer. The energy of activation for the souring of milk is$ (1) $2.303 \times 10 R kJ mol^{- 1}$ (2) $2.303 \times 5 R kJ mol^{- 1}$ (3) $2.303 \times 3 R k J mol^{- 1}$ (4) $2.303 \times 2.7 R k J mol^{- 1}$ 138. $For A_{2} + B_{2} ⇌ 2 AB E_{a} for forward and backward reaction are 180 and 200 kJ mol^{- 1} respectively If catalyst lowers E_{a} for both reaction by 100 kJ mol^{- 1} . Which of the following statement is correct?$ (1) $Catalyst does not alter the Gibbs energy change of a reaction.$ (2) $The enthalpy change for the reaction is + 20 kJ mol^{- 1} .$ (3) $Catalyst can cause non-spontaneous reactions to occur.$ (4) $The enthalpy change for the catalyzed reaction is different from that of uncatalyzed reaction.$ 139. $For a reaction A \to B, enthalpy of reaction is - 4.2 kJ mol^{- 1} and enthalpy of activation is 9.6 kJ mol^{- 1} . The correct potential energy profile for the reaction is shown in option.$ (1) (2) (3) (4) 140. $A first order reaction has a specific reaction rate of 1 0^{- 2} se c^{- 1} . How much time will it take for 20 g of the reactant to reduce to 5 g ?$ (1) $138.6 sec$ (2) $346.5 sec$ (3) $693.0 sec$ (4) $238.6 sec$ 141. $Average rate of reaction 2 SO_{2 (g)} + O_{2 (g)} ⟶ 2 SO_{3 (g)}, is written as$ (1) $\frac{Δ ( SO _{2} )}{Δ t}$ (2) $- \frac{Δ ( O _{2} )}{Δ t}$ (3) $\frac{1}{2} \frac{Δ ( SO _{2} )}{Δ t}$ (4) $\frac{Δ ( SO _{3} )}{Δ t}$ 142. $The rate of the reaction: CH_{3} COOC_{2} H_{5} + NaOH \to CH_{3} COONa + C_{2} H_{5} OH is given by the equation Rate = k (CH_{3} COOC_{2} H_{5}) [NaOH] If concentration is expressed in mol L^{- 1}, the unit of k is$ (1) $Lmol -1 s^{- 1}$ (2) $mol^{- 2} L2 s^{- 1}$ (3) $s^{- 1}$ (4) $molL-1 s^{- 1}$ 143. $Which among the following equations represents Arrhenius equation?$ (1) $k = A e^{E_{a} / RT}$ (2) $k = A e^{RT / E_{a}}$ (3) $k = \frac{A}{e ^{E_{a} / RT}}$ (4) $k = \frac{A}{e ^{RT / E_{a}}}$ 144. $The given reaction, 2 F e C 1_{3} + S n C l_{2} \to 2 F e C l_{2} + S n C l_{4} is an example of$ (1) $third order reaction$ (2) $first order reaction$ (3) $second order reaction$ (4) $none of these$ 145. $Slope of the straight line obtained by plotting log_{10} k against 1/ T represents what term?$ (1) $- E_{a}$ (2) $- 2.303 E_{a} / R$ (3) $- E_{a} /2.303 R$ (4) $- E_{a} / R$ 146. $For a certain reaction, the rate = k [A]^{2} [B] . When the initial concentration of A is tripled keeping concentration of B constant, the initial rate would$ (1) $increase by a factor of three.$ (2) $decrease by a factor of nine.$ (3) $increase by a factor of six.$ (4) $increase by a factor of nine$ 147. $The relationship between rate constant and half-life period of zero order reaction is given by$ (1) $t_{1/2} = [A]_{0} 2 k$ (2) $t_{1/2} = \frac{0.693}{k}$ (3) $t_{1/2} = \frac{[ A ] _{0}}{2 k}$ (4) $t_{1/2} = \frac{2 [ A ] _{0}}{k}$ 148. $The following data is obtained during the first order thermal decomposition of 2 A_{(s)} ⟶ B_{(s)} + C_{(s)} at constant volume and temperature. S. No. Time Total pressure in Pascal 1. At the end of 10 minutes 300 2. After completion 200 The rate constant in min^{- 1} is$ (1) $0.0693$ (2) $6.93$ (3) $0.00693$ (4) $69.3$ 149. $For a chemical reaction A \to B, the rate of the reaction is 2 \times 10^{- 3} mol dm^{- 3} s^{- 1}, when the initial concentration is 0.05 mol dm^{- 3} . The rate of the same reaction is 1.6 \times 10^{- 2} mol dm^{- 3} s^{- 1} when the initial concentration is 0.1 moldm^{- 3} . The order of the reaction is$ (1) $0$ (2) $3$ (3) $1$ (4) $2$ 150. $The rate constant for a first order reaction is given by the following equation: l n K = 33.24 - \frac{2.0 \times 1 0 ^{4} K}{T} The Activation energy for the reaction is given by ______kJ m o l^{- 1} . (In Nearest integer) (Given: R = 8.3 JK"^{1} m o l^{- 1})$