Hydrocarbons

An alkene $X\left(\mathrm{C}_4 \mathrm{H}_8\right)$ on reaction with HBr gave $Y\left(\mathrm{C}_4 \mathrm{H}_9 \mathrm{Br}\right)$. Reaction of $Y$ with benzene in the presence of anhydrous $\mathrm{AlCl}_3$ gave Z which is resistant to oxidation with $\mathrm{KMnO}_4-\mathrm{KOH}$. What are $X, Y, Z$ respectively?