\(\begin{array}{l}
5)\\
CTHH:R{H_4}\\
\dfrac{{MR}}{{MR + 4}} = 75\% \Rightarrow MR = 12g/mol \Rightarrow R:Cacbon(C)\\
6)\\
{C_2}{H_4} + {H_2} \to {C_2}{H_6}\\
{C_2}{H_4} + {H_2}O \to {C_2}{H_5}OH\\
{C_2}{H_5}OH + {O_2} \to C{H_3}COOH + {H_2}O\\
C{H_3}COOH + {C_2}{H_5}OH \to C{H_3}COO{C_2}{H_5} + {H_2}O\\
{C_2}{H_4} + B{r_2} \to {C_2}{H_4}B{r_2}
\end{array}\)
