Determining molecular formula from skeletal structure

Steps:

• Count carbon atoms: the ring structure has 6 vertices, indicating 6 carbons.
• Identify heteroatoms: one oxygen attached to the ring, forming a hydroxyl group.
• Calculate hydrogens: each ring carbon has 1 H (5 from ring + 1 from OH), totaling 6 H for C6H6O.
• Verify formula: matches standard for phenolic compounds with aromatic ring.

Why A is correct:

• C6H6O follows the general formula for benzene derivatives like phenol, where the ring contributes C6H5 and OH adds H and O.

Why the others are wrong:

• B: Extra carbon would require additional bonds or chain, not present in the 6-carbon ring.
• C: Adds 4 extra hydrogens, implying saturated structure, but ring shows unsaturation.
• D: Extra carbon and 2 fewer hydrogens suggest triple bond or different unsaturation, inconsistent with the diagram.

Final answer: A