Identify Z in the following reaction 

$C{H}_{3}C{H}_{2}OH\stackrel{PB{r}_3}{\to }X\stackrel{Alc.KOH.}{\to }Y\underset{\left(ii\right)H_{2}O,heat}{\overset{\left(i\right)H_{2}S{O}_4,RT}{\to }}Z$

$\underset{Ethanol}{C{H}_{3}C{H}_{2}OH}\stackrel{PB{r}_3}{\to }\underset{\underset{\left(X\right)}{Bromoethane}}{C{H}_{3}C{H}_2-Br}$

In first step, nucleophilic substitution reaction occur to  form bromoethane (X). In next step, dehydrohalogenation reaction gives alkene i.e. ethane (Y). In final step, hydrolysis will be occur to form ethanol (Z).