For reaction `aA rarr xP`, when `[A] = 2.2 mM`, the rate was found to be `2.4mM s^(-1)`. On reducing concentration of `A` to half, the rate changes to `0.6 mM s^(-1)`. The order of reaction with respect to `A` is

Options

A. `1.5`
B. `2.0`
C. `2.5`
D. `3.0`

Answer

B

Explanation

`aArarr xP`
Rate of reaction `=[A]^(n)`
Order of reaction = a.
`[A]_(1)=2.2 mM, r_(1)=2.4 mM s^(-1)" …(i)"`
`[A]_(2)=(2.2)/(2)m M, r_(2)=0.6 mM s^(-1)" or, "(2.4)/(4)" … (ii)"`
On reducing the concentration of A to half, the rate of reaction is decreased by four times.
Rate of reaction `=[A]^(2)`
Order of reation =2.