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Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R . Assertion A :Phenolphthalein is a pH dependent indicator, remains colourless in acidic solution and gives pink colour in basic medium Reason R : Phenolphthalein is a weak acid. It doesn't dissociate in basic medium. In the light of the above statements, choose the most appropriate answer from the options given b

Options

  1. ABoth A and R are true and R is the correct explanation of A
  2. BBoth A and R are true but R is NOT the correct explanation of A .
  3. CA is true but R is false
  4. DA is false but R is true

Correct answer

C. A is true but R is false

Step-by-step solution

Phenolphthalein, ( C 20 H 14 O 4 ) , an organic compound of the phthalein family that is widely employed as an acid-base indicator. As an indicator of a solution’s pH, phenolphthalein is colourless below pH 8 . 5 and attains a pink to deep red hue above pH 9 . 0 . Phenolphthalein dissociate in basic medium HPh aq colourless ⇌ H + + Ph - Pink

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