A catalyst increases the rate of reaction by:

The correct answer is Option (3) → Decreasing activation energy of reaction

A catalyst forms temporary bonds with the reactants and is given back unchanged at the end. It provides an alternative pathway of lower activation energy, so a larger fraction of the molecules has enough energy to react and the reaction becomes faster.

Why the other options are incorrect

• Option (1) Decreasing enthalpy of reactants — Incorrect. A catalyst does not change the energy of the reactants or of the products, so the enthalpy change of the reaction stays the same.

• Option (2) Increasing internal energy of reactants — Incorrect. A catalyst supplies no energy to the reactants; it lowers the energy barrier instead.

• Option (4) Increasing activation energy of reaction — Incorrect. A higher activation energy would mean fewer molecules able to react, so the reaction would become slower, not faster.

NCERT (2026-27 edition):
Effect of Catalyst – …

Note: The same/similar question has been asked in different years by NTA as per the details given below: