Answer:
a. first-order in both A and B.
Explanation:
In order to determine the kinetics of reaction let us consider the given data
a) Doubling the concentration of B while keeping the concentration of A fixed doubles the rate of the reaction. : it means the reaction is first order reaction with respect to reactant B.
b) The half life is the time required to complete the reaction by half way.
As with time one half of A remains and after equal time one fourth of A remains it means again the order of reaction is first with respect to A also.
There is no effect on the half life if we are decreasing the initial concentration of A also.
