Benzaldehyde C6H5CHO is an aromatic aldehyde. The functional group present in benzaldehyde is the aldehyde group, which is represented by the structure -CHO. The aldehyde group consists of a carbonyl group C=O with a hydrogen atom attached to the carbonyl carbon.When benzaldehyde reacts with Tollen's reagent ammoniacal silver nitrate, [Ag NH3 2]NO3 , it undergoes an oxidation reaction. Tollen's reagent is a mild oxidizing agent that selectively oxidizes aldehydes to carboxylic acids without affecting other functional groups like C=C double bonds.The chemical reaction between benzaldehyde and Tollen's reagent can be represented as follows:C6H5CHO + 2[Ag NH3 2]NO3 + 3H2O C6H5COOH + 2Ag + 4NH3 + 2HNO3In this reaction, benzaldehyde C6H5CHO is oxidized to benzoic acid C6H5COOH , while the silver ions in Tollen's reagent are reduced to metallic silver Ag . The formation of metallic silver as a precipitate is a positive test for the presence of an aldehyde functional group. This reaction is also known as the "silver mirror test" because the metallic silver formed can deposit on the inner surface of the test tube, creating a shiny silver mirror appearance.