If rate of reaction between a and B is expressed as `k[A][B]^2` , the reaction is

Explanation

Rate law expression is,
Rate=`k[A][B]^(1//2)`
`therefore` Order = 1+`1/2`=`1(1)/(2)`
For an elementry reaction,
Molecularity = Order
`therefore` Molecularity = `1(1)/(2)`
This is not possible because molecularity of a reaction cannot be a fraction. Hence the reaction cannot be an elementry reaction