Chemical Kinetics PYQs Set 2 (PDF)

Set 2 of 8 · Questions 31-60 of 224

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Mere Teacher · Previous Year Questions NEET Chemistry · Chemical Kinetics · Set 2 (Q31-60)
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31. $Reaction A (g) \to 2 B (g) + C (g) is a first order reaction. It was started with pure A t / min Pressure of system at time t / mm Hg 10160 \infty 240 Which of the following option is incorrect?$ (1) $Initial pressure of A is 80 mm Hg$ (2) $The reaction never goes to completion$ (3) $Partial pressure of A after 10 minute is 40 mm Hg$ (4) $Rate constant of the reaction is 1.693 min^{- 1}$ 32. $The rate of a reaction doubles, when the temperature is changed from 300 K to 310 K . Activation energy of the change is_______((R = 8.314 JK^{- 1} mol^{- 1}, log 2 = 0.301)$ (1) $53.6 kJ mol^{- 1}$ (2) $48.6 kJ mol^{- 1}$ (3) $58.5 kJ mol^{- 1}$ (4) $60.5 kJ mol^{- 1}$ 33. $For the reaction 2 A + B ⟶ product, rate of the reaction is 15 \times 10^{- 2} mol dm^{- 3} sec^{- 1} . When [A] = 0.3 moldm^{- 3} and [B] = 0.05 mol dm^{- 3} . What is the value of rate constant if reaction is first order in both the reactants?$ (1) $5$ (2) $8$ (3) $10$ (4) $2$ 34. $For a first order reaction A \to Products, initial concentration of A is 0.1 M , which becomes 0.001 M after 5 minutes. Rate constant for the reaction in min^{- 1} is$ (1) $0.2303$ (2) $1.3818$ (3) $0.9212$ (4) $0.4606$ 35. $Calculate the molar mass of solute when 1.5 gram non volatile solute dissolved in 100 mL solvent having density 0.8 g mL^{- 1} lowers its freezing point by 0.75 K . (Freezing point depression constant for solvent is 5 K kg mol^{- 1})$ (1) $100 g mol^{- 1}$ (2) $125 g mol^{- 1}$ (3) $110 g mol^{- 1}$ (4) $75 g mol^{- 1}$ 36. $For the reaction, 2 A + B \to products, when the concentrations of A and B both were doubled, the rate of the reaction increased from 0.3 mol L^{- 1} s^{- 1} to 2.4 mol L^{- 1} s^{- 1} . When the concentration of A alone is doubled, the rate increased from 0.3 and L^{- 1} s^{- 1} to 0.6 mol L^{- 1} s^{- 1} . Which one of the following statements is correct ?$ (1) $Total order of the reaction is 4$ (2) $Order of the reaction with respect to B is 2$ (3) $Order of the reaction with respect to B is 1$ (4) $Order of the reaction with respect to A is 2$ 37. $The rate constant and half life of a first order reaction are related to each other as$ (1) $t_{1/2} = \frac{0.693}{k}$ (2) $t_{1/2} = 0.693 k$ (3) $k = 0.693 t_{1/2}$ (4) $k t_{1/2} = \frac{1}{0.693}$ 38. $The rate of a first order reaction doubles when the temperature changes from 300 K to 310 K . The activation energy of the reaction (in kJ mol^{- 1}) is (R (= 8.3 JK^{- 1} mol^{- 1}, log 2 = 0.3)$ (1) $43.33$ (2) $53.33$ (3) $63.33$ (4) $73.33$ 39. $A \to products, is a first order reaction. The time required to decompose A to half its initial amount is 60 minutes. The rate constant of the reaction (in s^{- 1}) is$ (1) $1.05 \times 10^{- 2}$ (2) $1.15 \times 10^{- 2}$ (3) $1.25 \times 10^{- 4}$ (4) $1.92 \times 10^{- 4}$ 40. $The rate constant for a zero order reaction A \to products is 0.0030 mol L^{- 1} s^{- 1} . How long it will take for the initial concentration of A to fall from 0.10 M to 0.075 M ?$ (1) $10$ (2) $20 s$ (3) $8.33 s$ (4) $1.33 s$ 41. $If a reaction follows the Arrhenius equation, the plot Ink vs \frac{1}{( RT )} gives staright line with a gradient (- y) unit. The energy required to activate the reactat is :$ (1) $y/R unit$ (2) $y unit$ (3) $yR unit$ (4) $-y unit$ 42. $Calculate the activation energy of a reaction, whose rate constant doubles on raising the temperature from 300 K to 600 K .$ (1) $3.45 kJ / mol$ (2) $6.90 kJ / mol$ (3) $9.68 kJ / mol$ (4) $19.6 kJ / mol$ 43. $For the reaction 5 Br^{-} (aq) + 6 H^{+} (aq) + BrO_{3}^{-} (aq) ⟶ 3 Br_{2} (aq) + 3 H_{2} O (l) if, - \frac{Δ ( BrO _{3}^{-} )}{Δ t} = 0.01 mol L^{- 1} min^{- 1}, \frac{Δ ( Br _{2} )}{Δ l} in mol L^{- 1} min^{- 1} is$ (1) $0.01$ (2) $0.3$ (3) $0.03$ (4) $0.005$ 44. $For a reaction \frac{1}{2} A ⟶ 2 B, rate of disappearance of A is related to rate of appearance of B by the expression$ (1) $\frac{- d [ A ]}{dt} = \frac{1}{4} \frac{d [ B ]}{dt}$ (2) $\frac{- d [ A ]}{dt} = 4 \frac{d [ B ]}{dt}$ (3) $\frac{- d [ A ]}{dt} = \frac{1}{2} \frac{d [ B ]}{dt}$ (4) $\frac{- d [ A ]}{dt} = \frac{d [ B ]}{dt}$ 45. $The rate equation for a reaction A \to B is r = k [A]^{0} . If the initial concentration of the reactant is a mol dm^{- 3}, the half life period of the reaction is$ (1) $k / a$ (2) $a / k$ (3) $2 a / k$ (4) $a /2 k$ 46. $Half life periods for a reaction at initial concentrations of 0.1 M and 0.01 M are 5 and 50 minutes, respectively. The order of reaction is$ (1) $3$ (2) $2$ (3) $1$ (4) $0$ 47. $For the elementary reaction, 2 SO_{2 (g)} + O_{2 (g)} \to 2 SO_{3 (l)}, identify the correct relation among the following.$ (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) $+ \frac{d ( SO _{2 (g)} )}{dt} = - \frac{d ( O _{2 (g)} )}{dt}$ 48. $The half-life period of a first order reaction is 60 minutes. What percentage will be left over after 240 minutes?$ (1) $6.25 %$ (2) $4.25 %$ (3) $5 %$ (4) $6 %$ 49. $The time required for completion of 93.75 % of a first order reaction is x minutes. The half life of it (in minutes) is$ (1) $x /8$ (2) $x /2$ (3) $x /4$ (4) $x /3$ 50. $Consider an elementary reaction A (g) + B (g) \to C (g) + D (g) If the volume of reaction mixture is suddenly reduced to \frac{1}{3} of its initial volume, the reaction rate will become ' x' times of the original reaction rate. The value of x is:$ (1) $3$ (2) $\frac{1}{9}$ (3) $9$ (4) $\frac{1}{3}$ 51. $For the reaction O_{3 (g)} + O_{(g)} ⟶ 2 O_{2 (g)}, if the rate law expression is, rate = k (O_{3}) [O] the molecularity and order of the reaction are respectively$ (1) $2 and 2$ (2) $2 and 1.33$ (3) $2 and 1$ (4) $1 and 2$ 52. $For a first order reaction (A \to B), the temperature (T) dependent rate constant (k) in s^{- 1} was found to follow the equation : lo g k = - \frac{20}{T} + 4 . The activation energy (E_{a}) and preexponential factor (A) respectively, are$ (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) $9.212 c a l m o l^{- 1} and 1 0^{- 4} s^{- 1}$ 53. $What will be the overall order of a reaction for which the rate expression is given as Rate = k [A]^{\frac{1}{2}} [B]^{\frac{3}{2}}$ (1) $second order$ (2) $first order$ (3) $zero order$ (4) $third order$ 54. $In the chemical reaction A \to B, what is the order of the reaction? Given that, the rate of reaction doubles if the concentration of A is increased four times.$ (1) $2$ (2) $1.5$ (3) $0.5$ (4) $1$ 55. $A flask contains a mixture of compounds A and B. Both compounds decompose by first-order kinetics. The half-lives for A and B are 300 s and 180 s, respectively. If the concentrations of A and B are equal initially, the time required for the concentration of A to be four times that of B (in s) is : (Use 2 = 0.693)$ (1) $120$ (2) $300$ (3) $180$ (4) $900$ 56. $The rate law for the reaction A + B \to product is rate = k [A] [B] . When will the rate of reaction increase by factor two?$ (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) $[A] is kept constant and [B] is halved$ 57. $The slope of Arrhenius Plot (ln Kv / s 1/ T) of first order reaction is - 5 \times 10^{3} K . The value of E_{a} of the reaction is. Choose the correct option for your answer. [Given R = 8.314 JK^{- 1} mol^{- 1}]$ (1) $83.0 kJ mol^{- 1}$ (2) $166 kJ mol^{- 1}$ (3) $- 83 kJ mol^{- 1}$ (4) $41.5 kJ mol^{- 1}$ 58. $Half-life period of a first order reaction, A \to product is 6.93 hour. What is the value of rate constant?$ (1) $1.596 h^{- 1}$ (2) $4.802 h^{- 1}$ (3) $0.1 h^{- 1}$ (4) $10 h^{- 1}$ 59. $Por a chemical reaction, rate law is, rate = k [A]^{2} [B] . If [A] is doubled at constant [B], the rate of reaction$ (1) $increases by a factor of 8$ (2) $increase by a factor of 4$ (3) $increases by a factor of 3$ (4) $increase by a factor of 2 .$ 60. $At 27^{\circ} C in presence of a catalyst, activation energy of a reaction is lowered by 10 kJ mol^{- 1} . The logarithm of ratio of \frac{k ( catalysed )}{k ( uncatalysed )} is.... (Consider that the frequency factor for both the reactions is same)$ (1) $1.741$ (2) $17.41$ (3) $3.482$ (4) $0.1741$