
\(-\mathrm{Cl}\) shows \(+\mathrm{M}\) and \(-\mathrm{I}\) but inductive effect dominates.
\(-\mathrm{NO}_2\) shows \(-\mathrm{M}\) and \(-\mathrm{I}\).
Electrophilic substitution \(\alpha \frac{1}{-\mathrm{M} \text { and }-\mathrm{I}}\)
\(\alpha+\mathrm{M} \text { and }+\mathrm{I}\)
Hence, order is \(\mathrm{B}>\mathrm{A}>\mathrm{C}>\mathrm{D}\).

$(I)\,\,C{H_2} = CH - \mathop C\limits^ \oplus {H_2}$
$(II)\,\,C{H_3} - CH_2 - \mathop C\limits^ \oplus {H_2}$
$1.\,\,\,\begin{array}{*{20}{c}}
{C{H_3} - C - {O^ - }} \\
{\,\,\,||} \\
{\,\,\,O}
\end{array}$ $2.\,\,CH_3O^-$ $3.\,\,CN^-$
$a$ અને $b$ ની બંધ લંબાઈની તુલના કરો