Compound 'A' with molecular formula `C_4H_9Br` is treated with aq. KOH solution. The rate of this reaction depends upon the concentration of the compound 'A' only. When another optically active isomer 'B' of this compound was treated with aq. KOH solution, the rate of reaction was found to be dependent on concentration of compound and KOH both.
Write down the structural formula of both compounds 'A' and 'B'.

Explanation

In cae of `S_(N^2)` reactions, nucleophile attacks from the backside. Hence, the product of hydrolysis will have inverted configuration w.r. to 2-bromobutane.