The rate of reaction `A + 2B rarr 3C` gets increased by 72 times when the concentration of A is tripled and that of B is doubled. The order of the reaction with present to A and B are….. And ….. Respectively.

Options

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

Answer

B

Explanation

`r=k[A]^(alpha) [B]^(beta)` …(i)
`72 r=k[3A]^(alpha) [2B]^(beta)` ….(ii)
Dividing eqn. (i) by eqn (ii) `72 = 3^(alpha)2^(beta)`
By substituting the given values of `alpha =2,beta =3` we have
`3^(alpha)xx2^(beta) =3^(2)xx2^(3) =9 xx 8 =72`.