\(\begin{array}{l}
a)\\
{C_2}{H_4} + {H_2}O \to {C_2}{H_5}OH\\
{C_2}{H_5}OH + {O_2} \to C{H_3}COOH + {H_2}O\\
C{H_3}COOH + {C_2}{H_5}OH \to C{H_3}COO{C_2}{H_5} + {H_2}O\\
2{C_2}{H_5}OH + 2Na \to 2{C_2}{H_5}ONa + {H_2}\\
2C{H_3}COOH + Mg \to {(C{H_3}COO)_2}Mg + {H_2}\\
b)\\
{C_2}{H_5}OH + {O_2} \to C{H_3}COOH + {H_2}O\\
C{H_3}COOH + {C_2}{H_5}OH \to C{H_3}COO{C_2}{H_5} + {H_2}O\\
C{H_3}COO{C_2}{H_5} + NaOH \to C{H_3}COONa + {C_2}{H_5}OH\\
c)\\
{C_2}{H_5}OH + {O_2} \to C{H_3}COOH + {H_2}O\\
C{H_3}COOH + {C_2}{H_5}OH \to C{H_3}COO{C_2}{H_5} + {H_2}O\\
C{H_3}COO{C_2}{H_5} + NaOH \to C{H_3}COONa + {C_2}{H_5}OH
\end{array}\)