IR peaks identify functional groups by characteristic wavenumbers

Steps:

• Empirical formula C₂H₄O has one degree of unsaturation, suggesting structures like vinyl alcohol (with O-H and C-H) or acetaldehyde (with C=O and C-H).
• Recall IR stretch regions: C-H at 2800–3000 cm⁻¹ (sharp), O-H at 3200–3600 cm⁻¹ (broad due to H-bonding).
• Assign peak X to sharp absorption in C-H region and peak Y to broad absorption in O-H region, fitting an enol structure.
• Confirm no C=O (sharp ~1700 cm⁻¹) or prominent C-O (~1100 cm⁻¹) matches the given peaks.

Why B is correct:

• O-H stretch produces a broad peak from hydrogen bonding, diagnostic for alcohols or enols, aligning with C₂H₄O's possible vinyl alcohol form.

Why the others are wrong:

• A: C-O stretch occurs at lower ~1000–1300 cm⁻¹, not matching typical high-wavenumber peaks X/Y.
• C: O-H as peak X would show broadness, but X likely sharp for C-H.
• D: C=O stretch is sharp at ~1700 cm⁻¹, absent in O-H containing structure.

Final answer: B