Question

75$\%$ of a first order reaction was completed in 32 minutes. 50$\%$ of the reaction was complete in

• A. 4 min
• B. 8 min
• C. 16 min
• D. 24 min

Answer 1

The correct option is C 16 min

$t_{\frac{3}{4}}=\frac{2.303}{k}log\frac{a}{\frac{1}{4^a}}=\frac{2.303}{k}log4t_{\frac{3}{4}}=\frac{2.303}{k}log\frac{a}{\frac{1}{2^a}}=\frac{2.303}{k}log2\therefore \frac{t_{\frac{3}{4}}}{t_{\frac{1}{2}}}=\frac{log4}{log2}=2\therefore t_{\frac{1}{2}}=\frac{t_{\frac{3}{4}}}{2}=\frac{32}{2}=16min$