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

To solve the question, we need to identify the structural formulas of compounds 'A' and 'B' based on the information given about their reactions with aqueous KOH.

### Step-by-Step Solution:

1. **Identify Compound 'A':**
- The molecular formula of compound 'A' is \( C_4H_9Br \).
- The reaction rate depends only on the concentration of compound 'A', indicating that it undergoes an SN1 reaction. This suggests that compound 'A' is likely a tertiary alkyl halide, which can form a stable carbocation.
- The structure of a tertiary alkyl halide with the formula \( C_4H_9Br \) can be represented as follows:
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