JEE Main · 2020 · 07 Jan 2020 · Shift 1 · Compounds Containing Nitrogen

Consider the following reaction:

The product 'X' is used

(A)in protein estimation as an alternative to ninhydrin
(B)as food grade colourant
(C)in laboratory test for phenols
(D)in acid-base titration as an indicator✓ Correct

Answer: (D)

Solution

Heating phthalic anhydride with phenol under acid gives the condensation product phenolphthalein. Being colourless in acid and pink in base, phenolphthalein is the familiar indicator used to mark the end point in acid–base titrations.

JEE Main · 2020 · 07 Jan 2020 · Shift 1 · Single correct option

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