Question

Aldehyde and ketone can be distinguished by :
(1) Tollen's reagent
(2) Fehling's reagent
(3) $2,4$ -DNP
(4) $NaHCO _{3}$

• A. 1, 2 and 3 are correct
• B. 1 and 2 are correct
• C. 2 and 4 are correct
• D. 1 and 3 are correct

Answer 1

Answer: (B)

Aldehyde gives positive test with Tollen's reagent and Fehling's reagent while ketone's do not give these test.
$R C H O+ \underset{\text { Tollen's reagent }}{Ag _{2} O} \longrightarrow RCOOH +\underset{\text{silver mirror}}{2 Ag}$
$R C H O+\underset{\text { Fehling's reagent}}{2 C u O} \ce{->[{\Delta}]} R COOH + \underset{\text{red ppt.cuprous oxde}}{Cu _{2} O}$