Identify $Z$ in the following series: $C_2H_5I$ $\xrightarrow{Alco. KOH} X$ $\xrightarrow{Br_2} Y$ $\xrightarrow{KCN} Z$

Reaction of ethanol with conc. sulphuric acid at $170^{\circ} C$ produces a gas which is then treated with bromine in carbon tetrachloride. The major product obtained in this reaction is

Write the halogenation reaction of alkenes.

Ozonolysis of the given compound yields:

Alkene can be prepared from alkyl halide by the following reagent: $R-CH_2-CH_2-X + \text{Base} o \text{Alkene} + \text{Base-H} + X^-$

The main product of the following reaction $(1 \ mol)$ will be:
$C_6H_5-CH_2-CH=CH_2 + HBr \rightarrow \text{Products}$