Identify the major product $(P)$ in the following reaction sequence.

$$ \left(\mathrm{CH}_3\right)_3 \mathrm{CBr} \xrightarrow[\text { KOH, } \Delta]{\text { Alcoholic }} X \xrightarrow{\mathrm{HBr}} P $$

What is the percentage of carbon in the product ' $X$ ' formed in the given reaction?

$+\mathrm{C}_2 \mathrm{H}_5 \mathrm{Cl} \xrightarrow[\mathrm{AlCl}_3]{\text { Anhydrous }} X$

Which of the following is an example of allylic halide?

A halogen compound $X\left(\mathrm{C}_4 \mathrm{H}_9 \mathrm{Br}\right)$ on hydrolysis gave alcohol $Y$. The alcohol $Y$ undergoes dehydration with $20 \% \mathrm{H}_3 \mathrm{PO}_4$ at 358 K . What is $X$ ?