Question

The distinction between aldehydes and ketones can be made using:

• A. Conc. \(H_2SO_4\)
• B. Anhydrous \(ZnCl_2\)
• C. Schiff reagent
• D. Resorcinol

Hint:

Look for a reagent that only aldehydes turn pink. Think Schiff's (fuchsin) reagent.

Answer 1

The Correct Option is C

Step 1: Pick a test specific to the -CHO group. Aldehydes carry a hydrogen on the carbonyl carbon and are easily oxidised; ketones are not.
Step 2: Schiff's test. Schiff's reagent is fuchsin dye bleached by sulphur dioxide. An aldehyde reacts with the reagent and brings back a characteristic pink to magenta colour within a short time.
Step 3: Ketone behaviour. A ketone gives no colour (or only a very slow, faint one on standing), so the two classes are told apart by the immediate pink of the aldehyde.
Step 4: Conclusion. Schiff's reagent is the correct distinguishing reagent.
\[\boxed{\text{Schiff reagent}}\]