When an organic compound [A] having molecular formula is treated with aqueous , the rate of…

When an organic compound [A] having molecular formula $\text{C}_4\text{H}_9\text{Br}$ is treated with aqueous $\text{KOH}$, the rate of reaction depends on concentration of compound [A] only. But when compound [B], with the same molecular formula, reacts with aqueous $\text{KOH}$, the rate of reaction depends on the concentration of compound [B] as well as of $\text{KOH}$. Compound [B] is a structural isomer of compound [A]. Identify compounds [A] and [B].