Predict the final product$($s$)$ for each sequence of reactions:

Excess $NaN{H}_2$

$($a$)$

EtCl

$H_2,$ Lindlar's catalyst

$($b$)$

$NaN{H}_2$

MeI

$9-BBN$

$H_2{O}_2,$NaOH

$($c$)$

$NaN{H}_2,H-C-=C-H$

${?}_{\{\begin{array}{c}\text{:}[HgS{O}_4]\\ S{O}_4,& H_{2}O\end{array}}^2$EtI

$?$