An aqueous solution ‘A’ turns phenolphthalein  solution pink. On addition to an aqueous solution  ‘B’ to ‘A’, the pink colour disappears. The following  statement is true for solution ‘A’ and ‘B’.  

(a) A is strongly basic and B is a weak base.  

(b) A is strongly acidic and B is a weak acid.  

(c) A has pH greater than 7 and B has pH less than 7.  

(d) A has pH less than 7 and B has pH greater than 7.  

 

Ans. 

Phenolphthalein-Teachoo.jpg

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Phenolphthalein is an indicator which is 

  • colorless in acidic solutions 
  • And, turns dark pink in basic solutions.

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Since 

  • A turns the color of solution to dark pink, it is basic in nature and has a pH more than 7.
  • On the other hand, when B is added to A, the pink color disappears. Therefore, B is acidic in nature and has a pH below 7


So, the correct option is (c)

 

  1. Class 10
  2. Chapter 2 Class 10 - Acids, Bases and Salts (Term 1)

About the Author

CA Maninder Singh's photo - Founder at Teachoo
CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo