The common name of the following compound is

The correct answer is Option (2) → Benzophenone

The structure shows a carbonyl group, C=O, with a phenyl group on each side: \( \ce{C6H5-CO-C6H5} \). It is a ketone. In the common system, ketones in which the carbonyl group is attached to a benzene ring are named with the ending “-phenone”, the first part showing the other group on the carbonyl carbon:

• \( \ce{C6H5COCH3} \): methyl on the carbonyl carbon, acetophenone (methyl phenyl ketone)

• \( \ce{C6H5COCH2CH3} \): ethyl on the carbonyl carbon, propiophenone (ethyl phenyl ketone)

• \( \ce{C6H5COC6H5} \): phenyl on the carbonyl carbon, benzophenone (diphenyl ketone)

So the given compound, diphenyl ketone, is benzophenone; its IUPAC name is diphenylmethanone.

NCERT (2026-27 edition):
Common Names – “… The common names of ketones are derived by naming two alkyl or aryl groups bonded to the carbonyl group. The locations of substituents are indicated by Greek letters, α α′, β β′ and so on beginning with the carbon atoms next to the carbonyl group, indicated as αα′. Some ketones have historical common names, the simplest dimethyl ketone is called acetone. Alkyl phenyl ketones are usually named by adding the name of acyl group as prefix to the word phenone.”