1
JEE Main 2026 (Online) 4th April Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Consider the first order reaction $\mathrm{R} \rightarrow \mathrm{P}$.

The fraction of molecules decomposed in the given first order reaction can be expressed as

A

$$ 1-e^{k_1 t} $$

B

$$ 1+e^{k_1 t} $$

C

$$ 1+e^{-k_1 t} $$

D

$$ 1-e^{-k_1 t} $$

2
JEE Main 2026 (Online) 2nd April Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Consider the reaction aX → bY, for which the rate constant at 30°C is $1 \times 10^{-3}\ \text{mol}^{-1}\ \text{L}\ \text{s}^{-1}$. 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. JEE Main 2026 (Online) 2nd April Evening Shift Chemistry - Chemical Kinetics and Nuclear Chemistry Question 11 English vs time 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

3
JEE Main 2026 (Online) 2nd April Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

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?

A

$t_{100\%} = (t_{1/2})^2$ and $t_{100\%} = (t_{1/2})^{-\infty}$

B

$t_{100\%} = 2t_{1/2}$ and $t_{100\%} = (t_{1/2})^{\infty}$

C

$t_{100\%} = 2t_{1/2}$ and $t_{100\%} = (2t_{1/2})^2$

D

$t_{100\%} = (t_{1/2})^{\infty}$ and $t_{100\%} = 2t_{1/2}$

4
JEE Main 2026 (Online) 28th January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

An organic compound undergoes first order decomposition. The time taken for decomposition to $\left(\frac{1}{8}\right)^{\text {th }}$ and $\left(\frac{1}{10}\right)^{\text {th }}$ of its initial concentration are $\mathrm{t}_{1 / 8}$ and $\mathrm{t}_{1 / 10}$ respectively.

What is the value of $\frac{\mathrm{t}_{1 / 8}}{\mathrm{t}_{1 / 10}} \times 10$ ?

$$ (\log 2=0.3) $$

A

30

B

9

C

3

D

0.9

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