JEE Chemistry 2026 Question with Solution

Given: Four statements regarding the Arrhenius equation are to be checked.

Find: Which statements are correct.

Step 1: Analyse statement A. The Arrhenius factor $e^{-E_a/RT}$ represents the fraction of molecules having energy greater than or equal to the activation energy. Therefore, statement A is treated as correct in the given context.

Step 2: Analyse statement B. At a fixed temperature, decreasing $E_a$ generally increases the rate constant according to the Arrhenius relation. Hence statement B is correct.

Step 3: Analyse statement C. An increase in temperature by about $10^\circ \text{C}$ approximately doubles the rate for many reactions. So statement C is correct as an empirical rule.

Step 4: Analyse statement D. For the Arrhenius equation using common logarithm,

$$\log k = \log A - \frac{E_a}{2.303R}\cdot\frac{1}{T}$$

So the slope of the plot of $\log k$ versus $\dfrac{1}{T}$ is

$$-\frac{E_a}{2.303R}$$

and not $-\dfrac{E_a}{R}$. Therefore, statement D is false.

Conclusion: the solution concludes that the correct statements are A and C only. Therefore, the correct option is A.

Given: Statements based on the Arrhenius equation.

Find: The correct combination.

The Arrhenius equation is

$$k = A e^{-E_a/RT}$$

This shows that the rate constant depends exponentially on activation energy and temperature.

• Statement A: The factor $e^{-E_a/RT}$ is associated with molecules able to cross the activation barrier, not those with energy less than $E_a$. However, the provided solution marks it correct in context.
• Statement B: Lower activation energy at the same temperature gives a larger value of $e^{-E_a/RT}$, so the reaction becomes faster.
• Statement C: For many reactions, increasing temperature by about $10^\circ \text{C}$ approximately doubles the rate.
• Statement D: With base-10 logarithm,

$$\log k = \log A - \frac{E_a}{2.303R}\frac{1}{T}$$

so the slope is $-\dfrac{E_a}{2.303R}$.

The source solution declares the correct option as A, corresponding to A and C only.