$\begin{array}{*{20}{c}}
  {Ph - CH - CH - CHO\xrightarrow[\Delta ]{{{K_2}C{O_3}}}} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  {\,\,\,\,\,\,Br\,\,\,\,\,\,\,\,\,\,Br\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} 
\end{array}$

${H_2}C = CHC{H_2}Br\xrightarrow{{NaCN}}Y\xrightarrow[{2.\,{H_3}{O^ + }}]{\begin{subarray}{l} 
  1.{C_6}{H_5}MgBr\, \\ 
  diethylether 
\end{subarray} }Z$

$I.$ $DDT$                                        $II.$ Gammerane

$III.$ Carbon tetrachloride        $IV.$ Chlorobenzene

$(a)$ $\begin{array}{*{20}{c}}
  {C{H_3} - CH - Br} \\ 
  {|\,} \\ 
  {\,\,\,\,\,\,{C_2}{H_5}} 
\end{array}$

$(b)$ $\begin{array}{*{20}{c}}
  {\begin{array}{*{20}{c}}
  {\,\,Br} \\ 
  | 
\end{array}} \\ 
  {C{H_3} - C - C{H_3}} \\ 
  | \\ 
  {\,\,\,\,\,\,\,\,\,{C_2}{H_5}} 
\end{array}$

$(c)$ $\begin{array}{*{20}{c}}
  {C{H_3}{\mkern 1mu}  - CH{\mkern 1mu}  - {\mkern 1mu} {\mkern 1mu} C{H_2}Br} \\ 
  {|\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  {{C_2}{H_5}\,\,\,} 
\end{array}$