An organic compound 'X' is heated with phthalic anhydride in the presence of a few drops of concentrated H₂SO₄ . When the resulting mixture is made alkaline by adding dilute NaOH solution, a bright pink colour is produced. The compound 'X' is most likely:

Step-by-step solution

The given reaction is the phthalein dye test, which is a characteristic test for phenols. When phenol is heated with phthalic anhydride in the presence of concentrated H₂SO₄ , a condensation reaction takes place to form phenolphthalein. Phenolphthalein is an acid-base indicator which is colourless in acidic medium and turns bright pink in alkaline medium upon the addition of dilute NaOH . Therefore, the compound 'X' is phenol. Answer: Phenol