Question

Half life period of a first order reaction is 10 min. Starting with initial concentration 12M, the rate after 20 min is

• A. 0.0693 M min^-1
• B. 0.693 x 3 M min^-1
• C. 0.0693 x 3 M min^-1
• D. 0.0693 x 4 M min^-1

Answer 1

The correct option is C

0.0693 x 3 M min^-1

$t_{\frac{1}{2}}=10min$
$t_{\frac{1}{2}}=\frac{0.693}{10}=0.069312M\stackrel{10min}{\to }6M\stackrel{10min}{\to }3M$
$Rate=k\left[A\right]$

$Rate=0.0693\times 3Mmi{n}^{-1}$