An excess of ethyl chloride reacts with ${\mathrm{NH}}_3$ to give a

When $2-$bromo$-2-$methylbutane is heated with alcoholic $\mathrm{KOH}$, the possible products are _____.

$\left(\mathrm{i}\right) ({\mathrm{CH}}_3{)}_2\mathrm{C}={\mathrm{CHCH}}_3$

$$\begin{gathered} \left(\mathrm{ii}\right) {\text{CH}}_{\text{2}}\text{=}\underset{|}{\text{C}}{\text{-CH}}_{\text{2}}{\text{CH}}_{\text{3}} \\ {\text{ CH}}_{\text{3}} \end{gathered}$$

$\left(\mathrm{iii}\right) ({\mathrm{CH}}_3{)}_2\mathrm{CH}–\mathrm{CH}={\mathrm{CH}}_2$