Which of the following represents the decreasing order of reactivity towards reaction with ammonia?

Which of the following reactions produce ethyl cyanide $(CH_3 CH_2 CN)$ as a major product?
$1.$ $CH_3 CH_2 CH=NOH \xrightarrow{(CH_3 CO)_2 O} CH_3 CH_2 CN$
$2.$ $CH_3 CH_2 Cl \xrightarrow{\text{Ethanolic } KCN} CH_3 CH_2 CN$
$3.$ $CH_3 CH_2 Cl \xrightarrow{\text{Ethanolic } AgCN} CH_3 CH_2 NC$
$4.$ $CH_3 CH_2 CON(CH_3)_2 \xrightarrow[\text{Pyridine, } 70^{\circ} C]{C_6 H_5 SO_2 Cl} CH_3 CH_2 CN$

The following transformation can be carried out in three steps. The reagents required for these three steps in their correct order are:

The ester among the following is

Show how each of the following compounds can be converted to benzoic acid.
$(i)$ Ethylbenzene
$(ii)$ Acetophenone
$(iii)$ Bromobenzene
$(iv)$ Phenylethene (Styrene)

$CH_3-CO-CH_2-CH_2-CH_2-CO_2H \xrightarrow[(ii) H_2O, H^+]{(i) NaBH_4} ?$
What will be the final product of this transformation?