A compound 'X' when treated with phthalic anhydride in presence of concentrated \(\mathrm{H_2SO_4}\) yields 'Y'. 'Y' is used as an acid/base indicator. 'X' and 'Y' are respectively
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- Toludine, Phenolphthalein
- Carbolic acid, Phenolphthalein
- Salicylaldehyde, Phenolphthalein
- Anisole, methyl orange
The Correct Option is B
Solution and Explanation
Phenolphthalein is colourless in acidic medium and pink in basic medium, so it is used as an acid/base indicator (Y).
Thus X = carbolic acid (phenol) and Y = phenolphthalein.
Other options fail: toluidine and salicylaldehyde do not give a phthalein indicator, and methyl orange is made by diazo coupling, not from phthalic anhydride.
Answer: (2) Carbolic acid, Phenolphthalein
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