75% of a first order process is completed in $30 \min$. The time required for $93.75\%$ completion of same process (in hr) ?

$$\begin{gathered} \mathrm{k}=\frac{2.303}{\mathrm{t}}\log \left(\frac{\mathrm{a}}{\mathrm{a}-\mathrm{x}}\right), \\ \mathrm{k}=\frac{2.303}{30}\log \left(\frac{100}{100-75}\right)\dots \left(\mathrm{i}\right) \\ \mathrm{k}=\frac{2.303}{\mathrm{t}}\log \left(\frac{100}{100-93.75}\right) \\ \text{Put the value of }\mathrm{k}\text{ from above equation (i) we get } \\ \text{ the value of therefore } \\ \therefore \mathrm{t}=60\min \end{gathered}$$

As 60 min = 1 hr