CBSE Class 10 Answered

The oxidation of aldehydes can be performed with a mild oxidizing agent, such as Ag⁺  in
ammonia solution used in the Tollens test or Cu²⁺  in alkaline solution used in Fehling's test.  If
the Tollens test is performed in a scrupulously clean glass vessel, the silver metal is plated on the
walls of the glass to form a silver mirror.  Fehling's reagent is a deep blue Cu²⁺  solution that
forms a brick-red precipitate of Cu₂O in the presence of aldehydes.