Read the Passage carefully and answer the Questions.
Kinetic studies not only help us to determine the rate of a chemical reaction but also describe the conditions by which the reaction rates can be altered. The factors such as concentration, temperature, pressure and catalyst affect the rate of a reaction. The speed of a reaction or the rate of a reaction can be defined as the change in concentration of a reactant or product in unit time.
Rate = \( k [A]^x [B]^y \)
Here k is the rate constant
\( x + y \) gives the overall order of a reaction, whereas x and y represent the order with respect to the reactants A and B, respectively.
If the temperature is raised by 10 °C, then the rate of the reaction increases approximately by
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Two times
Most chemical reactions go faster at higher temperatures. It is found by experiment that for a rise in temperature of 10° the rate constant of a reaction is nearly doubled:
\( \displaystyle \frac{k_{t+10}}{k_{t}} \approx 2 \)
The reason is given by the Arrhenius equation, \( k = A\,e^{-E_a/RT} \). Raising the temperature increases the fraction of molecules having energy equal to or greater than the activation energy, and for a 10° rise near room temperature this fraction is roughly doubled. At the same concentrations the rate is proportional to k, so the rate of the reaction also becomes about two times.
Why the other options are incorrect
Option (2) Three times — Incorrect. For a 10° rise the rate constant is nearly doubled, not tripled.
Option (3) Five times — Incorrect. This is far more than the nearly doubled rate found for a 10° rise.
Option (4) Ten times — Incorrect. A 10° rise multiplies the rate by about 2, not by 10; the number 10 is the temperature rise, not the factor.
NCERT (2026-27 edition):
Temperature Dependence of the Rate of a Reaction – …
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | 02-06 S2 29-05 S2 | – | – | – |