Which of the following compounds will give Fehling's solution test?
(A) $CH_3CHO$
(B) $C_6H_5CHO$
(C) $CH_3CH_2CHO$
(D) $HCHO$
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (C) and (D) only
Core Concept
Fehling’s solution gives a positive test with aliphatic aldehydes but not with aromatic aldehydes.
Explanation
Option A: CH₃CHO (Acetaldehyde)
This is an aliphatic aldehyde. It reduces Fehling’s solution to form red precipitate of Cu₂O.
Option B: C₆H₅CHO (Benzaldehyde)
This is an aromatic aldehyde. Due to resonance stabilization of –CHO group with benzene ring, it does not reduce Fehling’s solution.
Option C: CH₃CH₂CHO (Propanal)
This is also an aliphatic aldehyde. Hence, it gives positive Fehling’s test.
Option D: HCHO (Formaldehyde)
Formaldehyde is the simplest aliphatic aldehyde. It readily reduces Fehling’s solution.