The half life period of a first order chemical reaction is 6.93 minutes. The time required for the completion of 99% of the chemical reaction will be $(\log 2=0.301)$

$$\begin{gathered} \text{ The half life period }{\mathrm{t}}_{1/2}=6.93\min \text{. } \\ \text{ The decay constant }\mathrm{\lambda }=\frac{0.693}{{\mathrm{t}}_{1/2}}=\frac{0.693}{6.93\min }=0.1/\min \\ \begin{array}{rl} & \mathrm{t}=\frac{2.303}{\mathrm{K}}\log \frac{\mathrm{a}}{\mathrm{a}-\mathrm{x}}\\ & \mathrm{t}=\frac{2.303}{0.1/\min }\log \frac{100}{100-99}\\ & \mathrm{t}=46.06\min \end{array} \\ \text{Hence, the time required for } \\ 99\mathrm{\%}\text{completion of the reaction is }46.06\min \end{gathered}$$