Acetone can be prepared by the oxidation of

Isopropyl alcohol

The correct answer is Option (2) → Isopropyl alcohol

Acetone (CH₃COCH₃) is prepared by the oxidation of isopropyl alcohol (2-propanol, CH₃CH(OH)CH₃) using oxidizing agents like acidified K₂Cr₂O₇ or PCC.

Reaction: CH₃–CH(OH)–CH₃ → CH₃–CO–CH₃ + H₂O

This is a standard laboratory/industrial method.

Why others are wrong:

• Methanol → oxidizes to formaldehyde → formic acid (no acetone)
• Ethanol → oxidizes to acetaldehyde → acetic acid (no acetone)
• Propanol (1-propanol) → oxidizes to propanal → propanoic acid (no acetone)

Only secondary alcohol with two methyl groups (isopropyl alcohol) gives a ketone (acetone) on oxidation.