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Chemical Kinetics · Question 20

JEE Main 2026 (Online) 23rd January Evening ShiftMCQEasy📈 Topic in 6% papers+4−1
1

[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

Answer

(4) 3

Solution

The falling curve is for A and the rising curve is for B.

In the first 10 min:

[A] = 0.04 - 0.05 = -0.01 M

[B] = 0.03 - 0 = 0.03 M

For A nB: - [A] t = 1n [B] t

n = [B]- [A] = 0.030.01 = 3

Answer: (4)

JEE Main 2026 (Online) 23rd January Evening Shift

Keep practising — Chemical Kinetics

2

Observe the following reactions at T(K). I. A products. II. 5Br-(aq) + BrO3-(aq) + 6H+(aq) 3Br2(aq) + 3H2O(l) Both the reactions are started at 10.00 am. The rates of these reactions at 10.10 am are same. The value of - [Br-] t at 10.10 am is 2 10-4 mol L-1 min-1. The concentration of A at 10.10 am is 10-2 mol L-1. What is the first order rate constant (in min-1) of reaction I?

  1. 4 10-3
  2. 2 10-3
  3. 10-3
  4. 10-2
JEE Main 2026 (Online) 23rd January Evening Shift
3

A product (First order reaction). Three sets of experiments were performed for a reaction under similar experimental conditions: Run 1 100 mL of 10 M solution of reactant A Run 2 200 mL of 10 M solution of reactant A Run 3 100 mL of 10 M solution of reactant A + 100 mL of H2O 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 1 < Run 2 < Run 3
  4. Run 3 < Run 1 = Run 2
JEE Main 2026 (Online) 22nd January Morning Shift
4

The temperature at which the rate constants of the given below two gaseous reactions become equal is K. (Nearest integer) X Y, k1 = 106 e -30000T P Q, k2 = 104 e -24000T Given : 10 = 2.303

JEE Main 2026 (Online) 22nd January Morning Shift
5

Correct statements regarding Arrhenius equation among the following are : Choose the correct answer from the options given below :

  1. A and B Only
  2. B and D Only
  3. B and C Only
  4. A and C Only
JEE Main 2026 (Online) 22nd January Evening Shift
6

Consider A k1 B and C k2 D are two reactions. If the rate constant (k1) of the A B reaction can be expressed by the following equation 10 k = 14.34 - 1.5 104T/K and activation energy of C D reaction (Ea2) is 15th of the A B reaction (Ea1), then the value of (Ea2) is kJ mol-1. (Nearest Integer)

JEE Main 2026 (Online) 22nd January Evening Shift
7

Pre-exponential factors of two different reactions of same order are identical. Let activation energy of first reaction exceed the activation energy of second reaction by 20 kJ mol-1. If k1 and k2 are the rate constants of first and second reaction respectively at 300 K, then k2k1 will be . (nearest integer) [R = 8.3 J K-1 mol-1]

JEE Main 2026 (Online) 21st January Morning Shift
8

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? ( 2 = 0.3)

  1. 6.9 10-4
  2. 6.9 10-3
  3. 6.9 10-1
  4. 6.9 10-2
JEE Main 2026 (Online) 21st January Evening Shift
9

In a first order decomposition reaction, the time taken for the decomposition of reactant to one fourth and one eighth of its initial concentration are t1 and t2 (s), respectively. The ratio t1/t2 will be:

  1. 43
  2. 32
  3. 34
  4. 23
JEE Main 2025 (Online) 8th April Evening Shift
10

A person's wound was exposed to some bacteria and then bacterial growth started to happen at the same place. The wound was later treated with some antibacterial medicine and the rate of bacterial decay (r) was found to be proportional with the square of the existing number of bacteria at any instance. Which of the following set of graphs correctly represents the 'before' and 'after' situation of the application of the medicine? [Given: N = No. of bacteria, t = time, bacterial growth follows 1st order kinetics.]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 7th April Morning Shift
11

Reaction A(g) 2B(g) + C(g) is a first order reaction. It was started with pure A. array|c|c| t/min & Pressure of system at time t/mm Hg \ 10 & 160 \ & 240 \ array 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 minutes is 40 mm Hg
  4. Rate constant of the reaction is 1.693 min-1
JEE Main 2025 (Online) 7th April Morning Shift

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