Which two compounds have the same empirical formula?

Correct answer: c glucose and acetic acid

Glucose, C₆H₁₂O₆, divided by 6 gives CH₂O; acetic acid, C₂H₄O₂, divided by 2 gives CH₂O. The empirical formulas match.

Why the other options are wrong

• a ethane and benzene: Ethane, C₂H₆, reduces to CH₃ and benzene, C₆H₆, to CH; the two differ.
• b ethane and ethene: Ethane, C₂H₆, gives CH₃ and ethene, C₂H₄, gives CH₂; both divide by 2 but the results differ.
• d benzene and hexane: Benzene, C₆H₆, gives CH and hexane, C₆H₁₄, gives C₃H₇; they differ.