Final answer:
The structure of the unknown compound hinted by NMR and IR spectroscopy data is likely a symmetrical molecule with a benzene ring, substituted with two methyl groups and a carbonyl function, possibly as a ketone or aldehyde. No O-H stretch in the IR spectrum excludes carboxylic acids.
Step-by-step explanation:
The unknown compound's structure can be deduced using NMR and IR spectroscopy data. The NMR data shows two chemical environments: one for 6 hydrogen atoms at a chemical shift of 2.82 ppm and another for 4 hydrogen atoms at 8.13 ppm. Both are singlets, suggesting symmetrical environments. The presence of 6 protons in the first environment implies the likely presence of two methyl groups attached to the same atom or group (e.g., a benzene ring, because two methyl groups attached to different carbons would show a different signal due to the influence of neighboring hydrogens).
The absence of an O-H stretch in conjunction with an IR absorption at 1681 cm-1 points to the presence of a carbonyl group, likely a ketone or aldehyde group since there's no indication of a carboxylic acid. Considering the data, a symmetrical structure with a benzene ring substituted with two methyl groups and possibly a ketone or aldehyde seems plausible.