$(a)\,\,CH_3CO_2^-$ $(b)\,\,H_2O$
$(c)\,\,CH_3SO_3^-$ $(d)\,\,\bar OH$
ione pair donating tendency on oxygen is reduced, nucleophilicity reduced \(b < c < a < d\)


$\begin{matrix}
\overset{\Theta }{\mathop{\overset{\centerdot \,\centerdot }{\mathop{C}}\,}}\,{{H}_{2}}-C-C{{H}_{3}} \\
|| \\
O \\
\end{matrix}$ અને $\begin{matrix}
C{{H}_{2}}=C-C{{H}_{3}} \\
| \\
:\underset{\Theta }{\mathop{\underset{\centerdot \,\centerdot }{\mathop{O}}\,}}\,: \\
\end{matrix}$

$(II)\,\,\,{{H}_{2}}C=CH-C{{H}_{2}}-\overset{+}{\mathop{C}}\,H-C{{H}_{3}}$
$(III)\,\,\,\begin{matrix}
\,\,\,\,\,C{{H}_{3}}\, \\
|\, \\
{{H}_{3}}C-C-\overset{+}{\mathop{C}}\,{{H}_{2}} \\
|\, \\
\,\,\,C{{H}_{3}} \\
\end{matrix}$
