Tiêu đề Chemical Kinetics -01.pdf ✅

1 JEE ADVANCED 2024 Chemical Kinetics Single Correct (1 – 9) 1. The rate of a reaction A + 2B → P is 2 × 10−2 M/ min, when concentrations of each A and B are 1.0 M. If the rate of reaction r = K [A]2 [B], the rate of reaction when half of the B has reacted should be (1) 5.625 × 10−3 M/min (2) 3.75 × 10−3 M/min (3) 9.375 M/min (4) 2.5 × 10−3 M/min 2. Which of the following statements is incorrect? (1) The order of reaction is the sum of powers of all the concentration terms in the rate equation. (2) The order of reaction with respect to one reactant is the ratio of the change of logarithm of the rate of the reaction to the change in the logarithm of the concentration of the particular reactant, keeping the concentrations of all other reactants constant. (3) Orders of reactions can be whole numbers or fractional numbers. (4) The order of a reaction can only be determined from the stoichiometric equation for the reaction. 3. Which of the following reactions is of fractional order? (1) Decomposition of N2O5. (2) Isomerization: CH3− NC → CH3− CN (3) Thermal decomposition of CH3 − CHO (4) Isomerization: → CH3 − CH = CH2 4. For the reaction A B C D ⎯⎯→ ⎯⎯→ ⎯⎯→ K K 1 2 K3 , where K3 > K2 > K1; the rate of formation of D is determined by (1) the rate of reaction: A → B (2) the rate of reaction: B → C (3) the rate of reaction: C → D (4) the rate of reaction: A → B with rate constant K1. K2. K3 5. A zero-order reaction A → B. At the end of 1 h, A is 75% reacted. How much of it will be left unreacted at the end of 2 h? (1) 12.5% (2) 6.25% (3) 3.12% (4) 0% 6. At the point of intersection of the two curves shown, the concentration of B is given as (A → nB) (1) A0 n (2) A0 n 1− (3) nA0 n 1+ (4) n 1A n 1 − + 7. The chemical reaction 2O3 → 3O2 proceeds as ( ) 1 2 K 3 2 K O O O fast + ( ) K3 O O 2O slow + ⎯⎯→ 3 2 The rate law expression will be (1) rate = K1 [O][O3 ] (2)rate = K1 [O3 ] (3) rate = K1⋅K3 K2 [O3 ] 2 [O2 ] (4)rate = K3 [O3 ] 2 [O2 ] 8. For the reaction 3A → 2B, the following graph is obtained experimentally. The rate of reaction when [A] = 0.2 M, is (1) 4 × 10−4Mmin−1 (2) 16 9 × 10−4Mmin−1 (3) 1.6 × 10−3Mmin−1 (4) 16 3 × 10−3Mmin−1 DPP - 01
2 9. The inversion of cane sugar proceeds with half-life of 500 minute at pH = 5 for any concentration of sugar. However, if pH = 6, the half-life changes to 50 minute. The rate law expression for the sugar inversion can be written as (1) r = K [sugar]2 [H + ] 0 (2) r = K [sugar] [H + ] 2 (3) r = K [sugar] [H + ] (4) r = K [sugar][H + ] −1 One or More than one Correct 10. For a complex (multistep) reaction, (1) the overall rate of reaction is the rate of slowest step. (2) the overall molecularity has no significance. (3) molecularity and order may or may not be same. (4) the number of rate determining steps may be more than one. 11. Which of the following statements is true? (1) The rate law for a reaction must depend on the concentrations of all reactants that appear in the stoichiometric equation. (2) The rate of a catalysed reaction must be independent of the concentration of catalyst. (3) The rate constant for the reaction is independent of the concentrations of the reacting species. (4) There is a single rate determining step in any reaction mechanism. 12. Which of the following is pseudo first-order reaction? (1) The basic hydrolysis of ethyl acetate. (2) The inversion of sucrose in the presence of an acid. (3) The acidic hydrolysis of ethyl acetate. (4) The decomposition of ammonium nitrite in aqueous solution 13. The order of reaction A → Products, may be given by which of the following expression(s)? (1) 2 1 2 1 ln ln ln[ ] ln[ ] − − r r A A (2)         0 0 2 1 1/2 1/2 2 1 ln ln ln ln − − A A t t (3)         0 0 2 1 1/2 1/2 2 1 ln ln 1 ln ln − + − A A t t (4) ln( / ) ln[ ] r K A Comprehension – 1 The thermal decomposition of N2O5 occurs as 2N2O5 → 4NO2 + O2. Experimental studies suggest that the rate of decomposition of N2O5, rate of formation of NO2 or rate of formation of O2, all becomes double if concentration of N2O5 is doubled. 14. The correct mechanism for the decomposition of N2O5 may be (1) Step-I: N2O5 ⎯⎯⎯→ Slow NO2 + NO3 Step-II: N2O5 + NO3 ⎯⎯⎯→Fast 3NO2 + O2 (2) Step-I: N2O5 ⎯⎯⎯→Fast NO2 + NO3 Step-II: N2O5 + NO3 ⎯⎯⎯→ Slow 3NO2 + O2 (3) N2O5 ⎯⎯⎯→Fast 2NO2 + 1 2 O2 (4) Step-I: N2O5 ⎯⎯⎯→Fast NO + NO2 + O2 Step-II: N2O5 + NO2 ⎯⎯⎯→ Slow 3NO2 + 1 2 O2 15. If the rate constants for decomposition of N2O5, formation of NO2 and formation of O2 are K1, K2 and K3, respectively, then (1) K1 = K2 = K3 (2) 2K1 = K2 = 4K3 (3) K1 = 2K2 = K3 (4) 2K1 = 4K2 = K3 16. If the rate of formation of O2 is 16 g/h, then the rate of decomposition of N2O5 and the rate of formation of NO2 are (1) 108 g/h, 92 g/h (2) 54 g/h, 46 g/h (3) 32 g/h, 64 g/hr (4) 16 g/h, 16 g/h
3 Integer Type Questions – Single Digit (0–9) 17. The number of reactions among the following, as written, could describe elementary reaction, is (i) Cl2 + CO → COCl2; r = K[Cl2 ] 3/2 [CO] (ii) PCl3 + Cl2 → PCl5; r = K[PCl3 ][Cl2 ] (iii) 2NO + H2 → N2O + H2O; r = K[NO][H2 ] (iv) 2NO + O2 → 2NO2; r = K[NO] 2 [O2 ] (v) NO + O3 → NO2 + O2; r = K[NO][O3 ] 18. The following mechanisms are proposed for the reaction CO + NO2 → CO2 + NO, at low temperature. Mechanism 1: 2NO2 ⇌ N2O4 (fast) N2O4 + 2CO → 2CO2 + 3NO (slow) Mechanism 2: 2NO2 → NO3 + NO NO3 + CO → NO2 + CO2 Which of the above mechanism is consistent with the observed rate law: + d[CO2 ] dt = K[NO2 ] 2 ? 19. For the reaction 3BrO− → BrO3 − + 2Br− in alkaline aqueous solution, the value of the second- order rate constant (in BrO− ) in rate law for − d[BrO−] dt was found to be 0.06M−1 s −1 . The rate constant (in M−1 s −1 ), when the rate law is written as + d[BrO3 −] dt is aM−1 s −1 and as + d[Br−] dt is bM−1 s −1 , then the value of (a + b) × 100 is Matrix – Match Type Questions 20. Match the columns. Column I Column II (A) Rate = k × Intensity of light (P) Second-orderss (B) Rate = k [A]1 [B]1 (Q) Zero-order (C) Rate = k [A]3/2[B]1/2 (R) First-order when A is excess (D) Rate = k [A]2 [B]1 (S) Second order when B is excess (1) A→Q; B→P, R; C→P; D→R, S (2) A→P, Q; B→Q, R; C→T, P; D→Q, R (3) A→P, S; B→Q, S; C→Q, P; D→Q, R (4) A→P, R; B→Q, T; C→Q, S; D→Q, R 21. Match the columns. Column I Column II (A) t1/2 = Constant (P) First-order (B) t1/2 ∝ a (Q) Third-order (C) t1 2 ∝ 1 a (R) Second-order (D) t1 2 ∝ 1 a 2 (S) Zero-order (1) A→P; B→S; C→R; D→Q (2) A→ Q; B→Q, R; C→T, P; D→Q, R (3) A→P, S; B→S; C→Q, P; D→Q, R (4) A→P, R; B→Q, T; C→Q, S; D→R s
4 Answer Key 1 . ( 1 ) 2 . ( 4 ) 3 . ( 3 ) 4 . ( 1 ) 5 . ( 4 ) 6 . ( 3 ) 7 . ( 3 ) 8 . ( 2 ) 9 . ( 4 ) 10 . (2, 1, 2, 3, 4 ) 11 . ( 3 ) 12 . (2. 3 ) 13 . (1, 3, 4 ) 14 . ( 1 ) 15 . ( 2 ) 16 . ( 1 ) 17 . ( 3 ) 18 . ( 2 ) 19 . ( 6 ) 20 . (1) 21 . (1)