Question:
The distinction between aldehydes and ketones can be made using:
The distinction between aldehydes and ketones can be made using:
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Look for a reagent that only aldehydes turn pink. Think Schiff's (fuchsin) reagent.
Updated On: Jul 10, 2026
- Conc. \(H_2SO_4\)
- Anhydrous \(ZnCl_2\)
- Schiff reagent
- Resorcinol
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The Correct Option is C
Solution and Explanation
Step 1: What is needed. We need a reagent that responds to aldehydes but not ketones.
Step 2: Schiff's reagent. Schiff's reagent is dilute rosaniline hydrochloride (magenta dye) decolourised by \(SO_2\). Aldehydes restore the pink/magenta colour, while ketones do not react.
Step 3: Apply. Add the unknown to Schiff's reagent: a pink colour appears with an aldehyde, no colour with a ketone. This cleanly distinguishes them.
Step 4: Why others fail. Conc. \(H_2SO_4\) and anhydrous \(ZnCl_2\) are dehydrating/Lewis-acid catalysts, not a selective test. Resorcinol is a phenol, not a differentiating reagent for this pair.
\[\boxed{\text{Schiff reagent (option iii)}}\]
Step 2: Schiff's reagent. Schiff's reagent is dilute rosaniline hydrochloride (magenta dye) decolourised by \(SO_2\). Aldehydes restore the pink/magenta colour, while ketones do not react.
Step 3: Apply. Add the unknown to Schiff's reagent: a pink colour appears with an aldehyde, no colour with a ketone. This cleanly distinguishes them.
Step 4: Why others fail. Conc. \(H_2SO_4\) and anhydrous \(ZnCl_2\) are dehydrating/Lewis-acid catalysts, not a selective test. Resorcinol is a phenol, not a differentiating reagent for this pair.
\[\boxed{\text{Schiff reagent (option iii)}}\]
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