b
$\begin{array}{*{20}{c}}
{O\,\,\,\,\,\,\,\,\,\,\,} \\
{||\,\,\,\,\,\,\,\,\,\,\,} \\
{Cl - C - O{C_2}{H_5}}
\end{array}\, + \,\,C{H_3}MgI\, \to \left[ {\begin{array}{*{20}{c}}
{OMgI\,} \\
{|\,\,\,\,\,\,\,\,\,\,\,} \\
{Cl - C - O{C_2}{H_5}} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,} \\
{C{H_3}\,\,\,\,\,\,}
\end{array}} \right]$
ઇથાઇલ ક્લોરો ફોર્મેટ મિથાઇલ મેગ્નેશિયમ આયોનાઇડ
$\xrightarrow{{{H_2}O/{H^ + }}} \begin{array}{*{20}{c}}
{Cl} \\
{Br}
\end{array} > Mg+ \, \begin{array}{*{20}{c}}
{O\,\,\,\,\,\,\,} \\
{||\,\,\,\,\,\,} \\
{C{H_3} - C - O{C_2}{H_5}}
\end{array}\,$