Question

Ratio of time required for $99\%$ and $90\%$ completion for a first order reaction is

• A. $\frac{2}{1}$
• B. $\frac{10}{9}$
• C. $\frac{9}{1}$
• D. $\frac{11}{10}$

Answer 1

Answer: (A)

$t_{99}=\frac{2.303}{k}\log \frac{100}{100-99}=\frac{2.303}{k}\times 2$
$t_{90}=\frac{2.303}{k}\log \frac{100}{100-90}=\frac{2.303}{k}\times 1$
$\frac{t_{99}}{t_{90}}=\frac{2}{1}$