Activation energy of a chemical reaction can be determined by _____.

determining the rate constant at two temperatures

The correct answer is Option (2) → determining the rate constant at two temperatures

To determine the activation energy (Ea), we use the Arrhenius equation:

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

Taking logarithms:

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

A plot of ln k vs 1/T at two different temperatures allows calculation of $E_a$.