Question

What is the test to differentiate between penta-2-one and pentan-3-one?

• A. lodoform test
• B. Benedict's test
• C. Fehling's test
• D. Tollen's test

Answer 1

The correct option is A lodoform test

The iodoform reaction been used as a chemical test for the presence of a methyl ketone moiety.
Acetone and acetaldehyde have methyl ketone moiety thus give iodoform reaction. Only those alcohols which contain $-CHOHC{H}_3$ group undergo haloform reaction.

Penta-2-one gives Tollen's test because it has methyl ketone moeity $(-COC{H}_3)$.but pentan-3-one does not because it doesnot have methyl ketone moeity $(-COC{H}_3)$.
Ketones donot respond to Tollen's, Fehling's and Benedict's test.
Hence option (a) is correct.