Chemical Kinetics PYQs Set 1 (PDF)

Set 1 of 8 · Questions 1-30 of 224

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Mere Teacher · Previous Year Questions NEET Chemistry · Chemical Kinetics · Set 1 (Q1-30)
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1. $A \to product (First order reaction). Three sets of experiment were performed for a reaction under similar experimental conditions: Run 1 \Rightarrow 100 mL of 10 M solution of reactant A Run 2 \Rightarrow 200 mL of 10 M solution of reactant A Run 3 \Rightarrow 100 mL of 10 M solution of reactant A + 100 mL of H_{2} O added. The correct variation of rate of reaction is$ (1) $Run 1< Run 2 < Run 3$ (2) $Run 3 < Run 1 < Run 2$ (3) $Run 3 < Run 1 = Run 2$ (4) $Run 1= Run 2 = Run 3$ 2. $The reaction 2 A \to 2 B + C has a rate constant of 1.2 \times 10^{- 2} s^{- 1} . Which of the following is correct?$ (1) $Plot of [A] vs " - \frac{1}{t} " will be straight line$ (2) $Plot of 1 [A] vs t^{2} will be a straight line$ (3) $Plot of ln [A] vs t will be a straight line$ (4) $Plot of [A] vs t^{2} will be a straight line$ 3. $2 A \to B + C It would be a zero order reaction when$ (1) $the rate of reaction is proportional to square of concentration of A$ (2) $the rate of reaction remains same at any concentration of A$ (3) $the rate remains unchanged at any concentration of B and C$ (4) $the rate of reaction doubles if concentration of B is increased to double.$ 4. $For a reaction A + B ⟶ P, the following data are provided Entry [A] in M [B] in M Initial rate (M / s) 1 0.02 0.02 2 \times 10^{- 2} 2 0.02 0.04 4 \times 10^{- 2} 3 0.04 0.04 8 \times 10^{- 2} The rate constant for this reaction in standard unit is$ (1) $5$ (2) $1.2$ (3) $2.4 \times 10^{- 4}$ (4) $50$ 5. $Higher order (> 3) reactions are rare due to$ (1) $shifting of equilibrium towards reactants due to elastic collisions$ (2) $loss of active species on collision$ (3) $low probability of simultaneous collision of all reacting species$ (4) $increase in entropy as more molecules are involved.$ 6. $For the reaction, 2 H_{2} (g) + 2 NO (g) \to N_{2} (g) + 2 H_{2} O (g) the observed rate expression is, rate = k_{f} [NO]^{2} [H_{2}] . The rate expression for the reverse reaction is:$ (1) $k_{b} = [N_{2}] [H_{2}]^{2} / [H_{2}]$ (2) $k_{b} = [K_{2}] [H_{2} O]^{2} / [H_{2}]$ (3) $k_{b} = [N_{2}] [H_{2} O]^{2} / [H_{2}]$ (4) $k_{b} = [N_{2}] [N_{2} O]^{2} / [H_{2}]$ 7. $Calculate the amount of reactant in percent that remains after 60 minutes involved in first order reaction (k = 0.02303) minute (^{- 1}) .$ (1) $25 %$ (2) $50 %$ (3) $75 %$ (4) $12.5 %$ 8. $Calculate half life of first order reaction if rate constant of reaction is 2.772 \times 10^{- 3} s^{- 1} .$ (1) $125 s$ (2) $250 s$ (3) $100 s$ (4) $150 s$ 9. $How enzymes increases the rate of reactions$ (1) $by lowering activation energy$ (2) $by increasing activation energy$ (3) $by changing equilibrium constant$ (4) $by forming enzyme substrate complex.$ 10. $The rate of a gaseous reaction is given by the expression, k [A] [B]^{2} . If the volume of vessel is reduced to one half of the initial volume, the reaction rate as compared to original rate is$ (1) $\frac{1}{16}$ (2) $\frac{1}{8}$ (3) $8$ (4) $16$ 11. $Which of the following statements is in accordance with the Arrhenius equation?$ (1) $Rate of a reaction increases with increase in temperature.$ (2) $Rate of reaction does not change with increase in activation energy.$ (3) $Rate constant decreases exponentially with increase in temperature.$ (4) $none of the above$ 12. $For a reaction A + B \to C + D if the concentration of A is doubled without altering the concentration of B, the rate gets doubled. If the concentration of B is increased by nine times without altering the concentration of A, the rate gets tripled. The order of the reaction is$ (1) $2$ (2) $1$ (3) $3/2$ (4) $4/3$ 13. $The rate law for the decomposition of hydrogen iodide is - \frac{d [ HI ]}{dt} = k [HI]^{2} . The units of rate constant k are$ (1) $L mol^{- 1} s^{- 1}$ (2) $L^{- 1} mol s^{- 1}$ (3) $L^{2} mol^{- 2} s^{- 1}$ (4) $L^{1/2} mol^{- 1/2} s^{- 1}$ 14. $For a reaction scheme A k_{1} B k_{2} C, if the rate of formation of B is set to be zero then the concentration of B is given by :$ (1) $(k_{1} - k_{2}) (A)$ (2) $k_{1} k_{2} (A)$ (3) $(k_{1} + k_{2}) (A)$ (4) $(\frac{k _{1}}{k _{2}}) (A)$ 15. $Half-life period of a first order reaction is 10 min . Starting with initial concentration 12 M, the rate after 20 min is$ (1) $0.693 \times 3 M min^{- 1}$ (2) $0.0693 \times 4 M min^{- 1}$ (3) $0.0693 M min^{- 1}$ (4) $0.0693 \times 3 M min^{- 1}$ 16. $Which one of the following statements for the order of a reaction is incorrect?$ (1) $Order can be determined only experimentally$ (2) $Order is not influenced by stoichiometric coefficient of the reactants.$ (3) $Order of a reaction is sum of power to the concentration terms of reactants to express the rate of reaction.$ (4) $Order of reaction is always whole number.$ 17. $Decomposition of A is a first order reaction at T (K) and is given by A (g) ⟶ B (g) + C (g) . In a closed 1 L vessel, 1 bar A (g) is allowed to decompose at T (K) . After 100 minutes, the total pressure was 1.5 bar. What is the rate constant (in min^{- 1}) of the reaction ? (log 2 = 0.3)$ (1) $6.9 \times 10^{- 3}$ (2) $6.9 \times 10^{- 4}$ (3) $6.9 \times 10^{- 1}$ (4) $6.9 \times 10^{- 2}$ 18. $3 A ⟶ 2 B, rate of reaction, + \frac{d [ B ]}{dt} is equal$ (1) $- \frac{3 d ⌊ A ⌋}{2 dt}$ (2) $- \frac{2 d [ A ]}{3 dt}$ (3) $+ 2 \frac{d [ A ]}{dt}$ (4) $- \frac{1}{3} \frac{d ∣ A ⌋}{dt}$ 19. $The addition of a catalyst during a chemical reaction alters which of the following quantities?$ (1) $Enthalpy$ (2) $Activation energy$ (3) $Entropy$ (4) $Internal energy$ 20. $The plot of t_{1/2} v / s [R]_{0} for a reaction is a straight-line parallel to x -axis. The unit for the rate constant of this reaction is$ (1) $mol L^{- 1} s$ (2) $molL-1 s^{- 1}$ (3) $Lmol^{- 1} s^{- 1}$ (4) $s^{- 1}$ 21. $For a reaction, the threshold energy is 75 kJ / mole . If the internal energy of the reactants is 20 kJ / mole, the activation energy (in kJ/mole) is$ (1) $55$ (2) $20$ (3) $75$ (4) $95$ 22. $The rate for reaction, A + B ⟶ product, is 1.8 \times 10^{- 2} mol dm^{- 3} s^{- 1} . Calculate the rate constant if the reaction is second order in A and first order in B . ([A] = 0.2 M; [B] = 0.1 M)$ (1) $9.0 mol^{- 2} dm^{6} s^{- 1}$ (2) $18.0 mol^{- 2} dm^{6} s^{- 1}$ (3) $4.5 mol^{- 2} dm^{6} s^{- 1}$ (4) $16.0 mol^{- 2} dm^{6} s^{- 1}$ 23. $For the reaction of H_{2} with I_{2} the rate constant is 2.5 \times 10^{- 4} d m^{3} mo l^{- 1} s^{- 1} at 327° C and 1.0 d m^{3} mo l^{1} s^{- 1} at 527° C . The activation energy for the reaction, in kJ mo l^{- 1} is : (R = 8.314 J K^{- 1} mo l^{- 1})$ (1) $166$ (2) $150$ (3) $72$ (4) $59$ 24. $The reaction 2 X \to B is a zeroth orer reaction. If the initial concentration of X is 0.2 M, the half-life is 6 h. When the initial concentration of X is 0.5 M, the time required to reach its final concentration of 0.2 M will be :$ (1) $9.0 h$ (2) $12.0 h$ (3) $18.0 h$ (4) $7.2 h$ 25. $Which one of the following is a second order reaction?$ (1) $H_{2} + Br_{2} ⟶ 2 HBr$ (2) $NH_{4} NO_{3} ⟶ N_{2} + 3 H_{2} O$ (3) $H_{2} + Cl_{2} \to Sunlight 2 HCl$ (4) $CH_{3} COOCH_{3} + NaOH ⟶ CH_{3} COONa + H_{2} O$ 26. $The time required for 60 % completion of a first order reaction is 50 min . The time required for 93.6 % completion of the same reaction will be$ (1) $83.8 min$ (2) $50 min$ (3) $150 min$ (4) $100 min .$ 27. $A reaction has rate constant k = 2.4 \times 10^{- 4} s^{- 1} . Then, find the ratio of t_{99.9} to t_{50} .$ (1) $1$ (2) $5$ (3) $10$ (4) $15$ 28. $If the rate constant for a first order reaction is k, the time (t) required for the completion of 99 % of the reaction is given by$ (1) $t = \frac{4.606}{k}$ (2) $t = \frac{2.303}{k}$ (3) $t = \frac{0.693}{k}$ (4) $t = \frac{6.909}{k}$ 29. $Rate law for a reaction between A and B is given by r = k [A]^{n} [B]^{m} If concentration of A is doubled and concentration of B is halved from their initial value, the ratio of new rate of reaction to the initial rate of reaction (\frac{r _{2}}{r _{1}}) is$ (1) $(n - m)$ (2) $2^{(n - m)}$ (3) $\frac{1}{2 ^{m + n}}$ (4) $(m + n)$ 30. $The half-life period of a first order reaction at 300 K and 400 K are 50 s and 10 s respectively. The activation energy of the reaction in kJ mol^{- 1} is (log 5 = 0.70)$ (1) $4.0$ (2) $8.0$ (3) $16.10$ (4) $20.10$