NEET 2026 (Phase 1) · ChemistryPrevious Year Question
The functional group that can be identified through the phthalein dye test is:
- A.(A) Aldehyde
- B.(B) Phenolic✓
- C.(C) Carboxylic acid
- D.(D) Alcohol
Correct Answer
(B) (B) Phenolic
Solution & Explanation
\textbf{Answer:} (B) Phenolic \textbf{Solution:} In the phthalein dye test, a phenol is heated with phthalic anhydride in the presence of concentrated \ce{H2SO4} to give phenolphthalein. The product turns pink/red on addition of \ce{NaOH} (alkali), confirming the presence of a phenolic (\ce{-OH}) group. Aldehydes, carboxylic acids and alcohols do not respond to this test.
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