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Chemical Kinetics · Question 10

JEE Main 2026 (Online) 2nd April Morning ShiftMCQMedium📈 Topic in 23% papers+4−1
1

t100\% is the time required for the 100% completion of the reaction while t1/2 is the time required for 50% of the reaction to be completed. Which of the following option correctly represents the relation between t100\% and t1/2 for zero and first order reactions respectively ?

  1. t100\% = (t1/2)2 and t100\% = (t1/2)-
  2. t100\% = 2t1/2 and t100\% = (t1/2)
  3. t100\% = 2t1/2 and t100\% = (2t1/2)2
  4. t100\% = (t1/2) and t100\% = 2t1/2

Answer

(2) t100\% = 2t1/2 and t100\% = (t1/2)

Solution

Zero order: [A] = [A]0 - kt

For 100% completion, [A] = 0 ⇒ t100\% = [A]0k

Half-life: t1/2 = [A]02k

∴ t100\% = 2t1/2

First order: t = 2.303k [A]0[A]

For 100% completion, [A] → 0 ⇒ [A]00 ⇒ t100\%

(after every t1/2 only half of what is left reacts, so the reaction is never 100% complete)

∴ for first order t100\% is infinite, written as (t1/2) .

Answer: (2)

JEE Main 2026 (Online) 2nd April Morning Shift

Keep practising — Chemical Kinetics

2

For reaction A P, rate constant k = 1.5 103 s-1 at 27°C If activation energy for the above reaction is 60 kJ mol-1, then the temperature (in °C) at which rate constant, k = 4.5 103 s-1 is . (Nearest integer) Given : log 2 = 0.30, log 3 = 0.48, R = 8.3 J K-1 mol-1, ln 10 = 2.3

JEE Main 2026 (Online) 2nd April Morning Shift
3

Consider the reaction aX bY, for which the rate constant at 30°C is 1 10-3 mol-1 L s-1. Which of the following statements are true? Choose the correct answer from the options given below:

  1. A and B Only
  2. A, B and C Only
  3. A, B, D and E Only
  4. C and D Only
JEE Main 2026 (Online) 2nd April Evening Shift
4

Consider the following gas phase reaction being carried out in a closed vessel at 25°C. 2A(g) 4B(g) + C(g) array|c|c| time (min) & total pressure of the system (mm Hg) \ 30 & 300 \ & 600 \ array The pressure of C(g) at 30 minutes time interval would be mm Hg. (nearest integer)

JEE Main 2026 (Online) 2nd April Evening Shift
5

An organic compound undergoes first order decomposition. The time taken for decomposition to ( 18 )th and ( 110 )th of its initial concentration are t1/8 and t1/10 respectively. What is the value of t1/8 t1/10 10? ( 2 = 0.3)

  1. 30
  2. 9
  3. 3
  4. 0.9
JEE Main 2026 (Online) 28th January Morning Shift
6

A → B (first reaction) C → D (second reaction) Consider the above two first-order reactions. The rate constant for first reaction at 500 K is double of the same at 300 K. At 500 K, 50% of the reaction becomes complete in 2 hours. The activation energy of the second reaction is half of that of first reaction. If the rate constant at 500 K of the second reaction becomes double of the rate constant of first reaction at the same temperature; then rate constant for the second reaction at 300 K is 10-1 hour-1 (nearest integer).

JEE Main 2026 (Online) 28th January Evening Shift
7

A D is an endothermic reaction occurring in three steps (elementary). (i) A B, Hi = +ve (ii) B C, Hii = -ve (iii) C D, Hiii = -ve Which of the following graphs between potential energy (y-axis) vs reaction coordinate (x-axis) correctly represents the reaction profile of A D?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2026 (Online) 24th January Morning Shift
8

At 27 in presence of a catalyst, activation energy of a reaction is lowered by 10 kJ mol-1. The logarithm of ratio of k (catalysed)k (uncatalysed) is.... (Consider that the frequency factor for both the reactions is same)

  1. 1.741
  2. 0.1741
  3. 17.41
  4. 3.482
JEE Main 2026 (Online) 24th January Morning Shift
9

The half-life of 65Zn is 245 days. After x days, 75\% of original activity remained. The value of x in days is . (Nearest integer) (Given: 3 = 0.4771 and 2 = 0.3010)

JEE Main 2026 (Online) 24th January Evening Shift
10

For the thermal decomposition of reactant AB(g), the following plot is constructed. [figure] The half-life of the reaction is 'x' min. x = min. (Nearest integer)

JEE Main 2026 (Online) 23rd January Morning Shift
11

[figure] Given above is the concentration vs time plot for a dissociation reaction : A nB. Based on the data of the initial phase of the reaction (initial 10 min), the value of n is .

  1. 2
  2. 5
  3. 4
  4. 3
JEE Main 2026 (Online) 23rd January Evening Shift

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