The reaction:

CH₃CH₂I + KOH (aq) →CH₃CH₂OH + KI is classified as:

(a) electrophilic substitution

(b) nucleophilic substitution

(c) elimination

(d) addition

Correct option is (a)

CH₃CH₂I + KOH (aq) →CH₃CH₂OH + KI

The reaction is an example of nucleopihlic substitution reaction. The hydroxyl group of KOH (OH^-) with a lone pair of itself acts as a nucleophile and substitutes iodide ion in CH₃CH₂I to form ethanol.