For the reaction, \(X + Y \longrightarrow Z\), the rate law expression is rate \(= k[X][Y]^3\). If the volume of the vessel is reduced to \(1/3\)rd of its original volume, then rate of reaction will:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → increase 81 times
When the volume of the vessel is reduced to one-third, the amount of each gas stays the same, so every concentration becomes three times.
Initial rate: r = k[X][Y]3
New rate: r′ = k(3[X])(3[Y])3 = 3 × 27 × k[X][Y]3
r′ = 81 r
So the rate increases 81 times.
NCERT (2026-27 edition):
Dependence of Rate on Concentration – “The rate of a chemical reaction at a given temperature may depend on the concentration of one or more reactants and products. The representation of rate of reaction in terms of concentration of the reactants is known as rate law. It is also called as rate equation or rate expression.”
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | – | – | 10-06 S1 08-06 S3 | – |