Question

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 below :

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is NOT the correct explanation of A.
• C. A is true but R is false
• D. A is false but R is true

Answer 1

Answer: (D)

Phenolphthalein dissociate in basic medium $\underset{\text{(Colourless)}}{HPh(aq)}\rightleftharpoons H^{+}+\underset{\text{(Pink)}}{P{h}^{-}}$