Select the correct statement.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A catalyst does not change the Gibbs energy and equilibrium constant of a reaction.
A catalyst gives the reaction an alternative path with a lower activation energy, so the reaction goes faster. It does not change the energies of the reactants and products, because it is recovered unchanged at the end.
It changes neither \( \Delta G \), which depends only on the initial and final states, nor the equilibrium constant.
\( \displaystyle \Delta G^\circ = -RT\ln K \)
This relation also shows that the two go together: if \( \Delta G^\circ \) is unchanged, K must be unchanged too. So a catalyst changes neither the Gibbs energy nor the equilibrium constant.
Why the other options are incorrect
Option (2) A catalyst changes the Gibbs energy but does not change the equilibrium constant of a reaction. — Incorrect. \( \Delta G \) is fixed by the initial and final states, which the catalyst does not change.
Option (3) A catalyst changes the equilibrium constant but does not change the Gibbs energy of a reaction. — Incorrect. The forward and backward rates are raised equally, so K stays the same.
Option (4) A catalyst changes both the Gibbs energy and equilibrium constant of a reaction. — Incorrect. It changes only the speed of the reaction, through the activation energy.
NCERT (2026-27 edition):
Effect of Catalyst – …
