Identify the product ' $B$ ' in the following sequence of reactions.

$$ \text { Ethanenitrile } \xrightarrow{\mathrm{SnCl}_2 . \mathrm{HCl}^{\mathrm{}}} \mathrm{~A} \xrightarrow{\mathrm{H}_3 \mathrm{O}^{+}} \mathrm{B}+\mathrm{NH}_4 \mathrm{Cl} $$

Identify secondary amine from following.

What is the number of moles of hydrogen atoms required to reduce one mole of nitroethane completely using Sn and HCl ?

Identify the substrate ' $A$ ' in the following conversion.

$$ \text { A } \xrightarrow[\mathrm{H}_3 \mathrm{O}^{+}]{\mathrm{AlH}_4\left(-\mathrm{Bu}_2\right)} \text { Pent-3-enal } $$