JEE Main 2026 — Apr 2, Shift 2 — Chemistry solution

JEE Main2026Apr 2, Shift 2Chemistry

Consider the reaction $a X \to bY$ , for which the rate constant at $3 0^{\circ}$ C is $1 \times 1 0^{- 3}$ mol $^{- 1}$ L s $^{- 1}$ . Which of the following statements are true ?

A. When concentration of 'X' is increased to four times, the rate of reaction becomes $16$ times.

B. The reaction is a second order reaction.

C. The half-life period is independent of the concentration of X.

D. Decomposition of N $_{2}$ O $_{5}$ is an example of the above reaction.

E. The plot

is valid for the above reaction.

Choose the correct answer from the options given below :

A
A and B only
B
A, B and C only
C
A, B, D and E only
D
C and D only

Solution

The units of $k$ are mol $^{- 1}$ L s $^{- 1} \equiv$ M $^{- 1}$ s $^{- 1}$ , which matches a second-order rate constant (general unit: M $^{1 - n}$ s $^{- 1}$ , so $1 - n = - 1$ , hence $n = 2$ ).

A. Rate $= k [X]^{2}$ , so quadrupling $[X]$ multiplies the rate by $16$ . $✓$

B. Order is $2$ . $✓$

C. For a second-order reaction $t_{1/2} = \frac{1}{k [ X ] _{0}}$ , which depends on initial concentration. $\times$

D. Decomposition of N $_{2}$ O $_{5}$ follows first-order kinetics. $\times$

E. The integrated rate law $ln \frac{[ R ] _{0}}{[ R ]} = k t$ is the first-order form, not second-order. $\times$

Only A and B are correct.

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