The hydrolysis of an ester was carried out separately with 0.05 M HCl and 0.05 M ${\mathrm{H}}_2{\mathrm{SO}}_4$ . Which of the following expressions is correct?

We will have ${\left[{\mathrm{H}}^{+}\right]}_{0.05{\mathrm{MH}}_2{\mathrm{SO}}_4}>{\left[{\mathrm{H}}^{+}\right]}_{0.05\mathrm{MHCl}}$

Since the rate constant is directly proportional to $\left[{\mathrm{H}}^{+}\right],$ it follows that $k_{\mathrm{HCl}}<k_{{\mathrm{H}}_2}{\mathrm{SO}}_4$

Hence, option B is correct.