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

Options

A. `0.0693 xx 4 M "min"^(-1)`
B. `0.0693 xx 3 M "min"^(-1)`
C. `0.693 xx 3 M "min"^(-1)`
D. `0.0693 M "min"^(-1)`

Answer

B

Explanation

`H//2 =1 0 min`
`K = 0.693/10 = 0.0693 mm^(-1)`
As H/2is 10 min, after 20 minutes the concentration will be 3m.
Hence, Rate `= 0.0693 xx 3m "min"^(-1)`