Explain how a hydroxynitrile is produced from a ketone

Hydroxynitriles are produced from ketones by a nucleophilic addition reaction. The negatively charged cyanide ion from KCN is attracted to the partially positive carbon on the carbonyl group. This causes one of the bonds on the Carbon-Oxygen double bond to break. This produces a negatively charged oxygen with a free lone pair of electrons. The lone pair acts as a nucleophile to a H+ in the HCl, adding it to produce a hydroxynitrile.