IR spectrum identifies ketone via carbonyl stretch without O-H band

Steps:

• Examine spectrum for broad O-H stretch (3200–3600 cm⁻¹), absent in Q, ruling out alcohols and acids.
• Identify strong C=O stretch around 1710–1715 cm⁻¹, indicating carbonyl group.
• Note absence of aldehyde C-H stretches (2700–2800 cm⁻¹), narrowing to ketone.
• Match to butanone's expected IR profile for C4H8O ketone.

Why C is correct:

• Butanone features isolated C=O stretch at 1710–1715 cm⁻¹ per Hooke's law for ketone vibration, without O-H interference.

Why the others are wrong:

• A: Butan-1-ol shows broad O-H stretch from hydrogen bonding, missing in Q's spectrum.
• B: Butanoic acid exhibits broad O-H and C=O at ~1710 cm⁻¹ with C-O bands, not matching Q.
• D: 3-Hydroxybutanal has broad O-H and aldehyde C-H stretches, absent in Q.

Final answer: C