Compound 'X' with molecular formula $\text{C}_4\text{H}_9\text{Br}$ reacts with aqueous $\text{KOH}$ to give an alcohol. The rate of this reaction depends only on the concentration of the compound 'X'. When an optically active isomer 'Y' of the compound 'X' was treated with aqueous $\text{KOH}$ solution, the rate of reaction was found to be dependent on concentration of compound 'Y' and aqueous $\text{KOH}$ both. (a) Write down the structural formula of both 'X' and 'Y'. (b) Out of 'X' and 'Y', which one will undergo racemisation and why ? (c) Out of 'X' and 'Y', which one will form product with inversion of configuration and why ?