Question

What happens when ethyl bromide reacts with KCN

Answer 1

Et-Br + NaCN or KCN →Et-CN i.e. cyanide will be formed.

Et-Br + AgCN → Et-NC i.e. isocyanide will be formed.

The reason for this is that NaCN and KCN are Ionic. Hence they have cyanide ion (CN-) in which the -ve charge lies on carbon. So, in the reaction C is our nucleophilic atom.

Answer 2

replace of br from ethyl bromide and addition of CN to it
means substitution
thanks bol do yr