JEE Main 2025 (Online) 8th April Evening Shift

MCQ (Single Correct Answer)

-1

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 $t_1$ and $t_2$ (s), respectively. The ratio $t_1/t_2$ will be:

$\frac{4}{3}$

$\frac{3}{2}$

$\frac{3}{4}$

$\frac{2}{3}$

JEE Main 2025 (Online) 7th April Evening Shift

MCQ (Single Correct Answer)

-1

A(g) → B(g) + C(g) is a first order reaction.

Time	t	∞
P_system	P_t	P_∞

The reaction was started with reactant A only. Which of the following expressions is correct for rate constant k?

$\mathrm{k}=\frac{1}{\mathrm{t}} \ln \frac{\mathrm{p}_{\infty}}{\mathrm{p}_{\mathrm{t}}}$

$\mathrm{k}=\frac{1}{\mathrm{t}} \ln \frac{\mathrm{p}_{\infty}}{2\left(\mathrm{p}_{\infty}-\mathrm{p}_{\mathrm{t}}\right)}$

$\mathrm{k}=\frac{1}{\mathrm{t}} \ln \frac{2\left(\mathrm{p}_{\infty}-\mathrm{p}_{\mathrm{t}}\right)}{\mathrm{p}_{\mathrm{t}}}$

$\mathrm{k}=\frac{1}{\mathrm{t}} \ln \frac{\mathrm{p}_{\infty}}{\left(\mathrm{p}_{\infty}-\mathrm{p}_{\mathrm{t}}\right)}$

JEE Main 2025 (Online) 7th April Morning Shift

MCQ (Single Correct Answer)

-1

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 $1^{\text {st }}$ order kinetics.]

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Chemical Kinetics and Nuclear Chemistry Question 9 English Option 1

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Chemical Kinetics and Nuclear Chemistry Question 9 English Option 2

JEE Main 2025 (Online) 7th April Morning Shift

MCQ (Single Correct Answer)

-1

Reaction $\mathrm{A}(\mathrm{g}) \rightarrow 2 \mathrm{~B}(\mathrm{~g})+\mathrm{C}(\mathrm{g})$ is a first order reaction. It was started with pure A

t/min	Pressure of system at time t/mm Hg
10	160
$\infty$	240

Which of the following option is incorrect?

Initial pressure of A is 80 mm Hg

The reaction never goes to completion

Partial pressure of A after 10 minute is 40 mm Hg

Rate constant of the reaction is $1.693 \mathrm{~min}^{-1}$

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