Account for the following :
Reduction of alkylcyanide forms primary amine whereas alkyl isocyanide forms secondary amine.

Explanation

The reduction of alkyl cyanides forms `1^(@)` - amines. In alkyl cyanides alkyl group is attached to carbon atom of cyanide. Where as in alkyl iso cyanides alkyl group is attached to nitrogen atom of isocyanide. So reduction of alkyl isocyanide forms `2^(@)` - amines.
`{:(R - CN overset(LiAlH_4)(to) R-CH_(2) - NH_(2)) , ("alkyl cyanide" " " 1^(@) - "amine"), (R- CN " " " "R- NH- CH_(3)), ("alkyl isocyamide" overset(NaHg, H_(2))(to) 2^(@) - "amine"):}`