For the elementary reaction `MrarrN`, the rate of disappearance of `M` increases by a factor of `8` upon doubling the concentration of `M`. The order of the reaction will respect to `M` is

Options

A. 4
B. 3
C. 2
D. 1

Answer

B

Explanation

For the elementary reachtion,
`MrightarrowN`Rate law can be written as
`Rateprop[M]^(n)`
`Rate=k[M]^(n)`When we double the concentration of[M] rate becomes 8 times, hence, new rate law can be written as
`8xxRate=k[2M]^(n)`
`(Rate)/(8xxRate)=(k[M]^(n))/(k[2M]^(n))implies(1)/(8)=(1)/([2]^(n))`
`[2]^(n)=8=[2]^(3)`
`n=3`