Formaldehyde and acetaldehyde both have alpha hydrogen. Thus, both compounds will show positive Fehling's test. The second reagent is ammoniacal silver nitrate, commonly called Tollen's reagent. ... Thus, both the given aldehydes will show a positive Tollens test.

Which aldehyde does not give Fehling's test?

Aldehydes such as benzaldehyde, lack alpha hydrogens and cannot form an enolate and thus do not give a positive test with Fehling's solution which is comparatively a weaker oxidizing agent than Tollen's reagent, under usual conditions.

Does formaldehyde react with Fehling's?

Formaldehyde (\[C{{H}_{2}}O\]) reacts with Fehling solution to form anion of formic acid.