An optically active organic compound P has molecular formula  $C_7{H}_{11}Br$, and it does not declourize bromine water. P on treatment with potassium tertiary butoxide in tertiary butanol yields Q $\left(C_7{H}_{10}\right)$. The compound Q on oxidation with acidified solution of $KMn{O}_4$ yields R $\left(C_7{H}_{10}{O}_4\right)$, which does not undergo intramolecular dehydration on heating with  $P_2{O}_5$. The compound R on heating with NaOH (CaO) gives S  $\left(C_5{H}_{10}\right)$. S on heating with dry bromine vapour given $T\left(C_5{H}_{9}Br\right)$ as only monobromo derivative