A hypothetical reaction `A_(2) + B_(2) rarr 2AB` follows the mechanism as given below:
`A_(2) hArr A+A ("fast")`
`A+B_(2) rarr AB+B` (slow)
`A+B rarr AB` (fast)
The order of the overall reaction is

Options

A. `2`
B. `1`
C. `1(1)/(2)`
D. zero

Answer

C

Explanation

Rate `= K[A][B_(2)]`
`K = ([A]^(2))/([A_(2)]) rArr [A] = {K[A_(2)]}^(1//2)`
`r = K'[A_(2)]^(1//2)[B_(2)] o rder = 1(1)/(2)`