Chemistry · Chemical Kinetics

JEE Main 2026 — 4 April, Evening Shift — Question 60

Consider the given graph showing variation of reactant concentration with time. Three different reactions were started with identical initial concentration of reactants. Which of the following statement is correct?

Option A:
The order of all the three reactions is same.
Option B:
The rate constant of reaction 3 is larger than the rate constant of reaction 2 if the order of reaction is same for both.
Correct
Option C:
The SI unit of rate constant of reaction 1 is $\mathrm{s}^{-1}$ .
Option D:
Thermal decomposition of HI on gold surface is an example of reaction 2 .

Answer: B

Step-by-step solution

⇒ Curve $\mathrm{I}^{\text {st }}$ represent zero order kinetics $\left[\mathrm{R}_{\mathrm{t}}\right]=[\mathrm{R}]_{0}-\mathrm{Kt}$ $\Rightarrow \mathrm{K}_{3}>\mathrm{K}_{2}$ ⇒ Reaction-1 is zero order having unit of rate constant same as rate of reaction i.e., molarity / second

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Exam: JEE Main 2026
Paper: 4 April, Evening Shift
Subject: Chemistry
Chapter: Chemical Kinetics
Topic: Basics of Rate of a Chemical Reaction

For a first order reaction A arrow B t/ min [A]/M --- --- 0 0.6500 x 0.0650 20 0.00065 x= \ \ \ \ min. (Nearest integer)

Answer: B

Step-by-step solution

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