The rate constant of acid hydrolysis of an ester with $\mathrm{pH}=3\text{ is }1.1\times {10}^{-4}{\mathrm{s}}^{-1}$. Its rate constant at

$\mathrm{pH}=2$ will be 

Acid-hydrolysis of an ester is first-order with respect to [H⁺]. Hence

$k_{\mathrm{pH}-2}=\left(k_{\mathrm{pH}=3}\right)\frac{{\left[{\mathrm{H}}^{+}\right]}_{\mathrm{pH}=2}}{{\left[{\mathrm{H}}^{+}\right]}_{\mathrm{pH}=3}}=\frac{1.1\times {10}^{-4}{\mathrm{s}}^{-1}}{\left[{10}^{-3}\right]}\left[{10}^{-2}\right]=11\times {10}^{-4}\mathrm{s}$