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

Initially, rate `r = k[M]^(alpha) = ka^(alpha) " "…(i)`
On doubling the concentration of M
Dividing eqn. (ii) by eqn. (i),
`8 =2^(alpha) or 2^(alpha) = 2^(3) or alpha = 3`