Question

A first order reaction is 50% completed in $1.26\times {10}^{14}s$. How much time would it take for 100% completion?

• A. $2.52\times {10}^{14}s$
• B. Infinite
• C. $2.52\times {10}^{28}s$
• D. $1.26\times {10}^{15}s$

Answer 1

The correct option is B Infinite

Reaction would be 100% complete only after infinite time which cannot be calculated.

For first order reaction,
$t=\frac{2.303}{k}log\frac{a}{a-x}$

$t=\frac{2.303}{k}log\frac{100}{0}$
$t=\infty$

Hence, option (d) is correct.