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

Let order with respect to M is `alpha`,
`:. R=k[M]^(alpha)" ".....(i)`
`8r=[2M]^(alpha)" ".....(i)`
Dividing eq. (ii) by eq. (i)
`8=2^(alpha)" " :. alpha=3`