Identify which of the following solutions will turn the phenolphthalein indicator pink in colour.

[0.8 mark]

Strong acid + Strong base

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Weak acid + Strong base

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

Strong acid + Weak base

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Strong acid + Weak acid

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is B Weak acid + Strong base
Phenolphthalein is an indicator used for acid-base reactions. Phenolphthalein is colourless in acidic solutions but changes its colour to pink in basic solutions.
The given combinations can be analysed as follows:

Combination Nature of salt

Strong acid + Strong base Neutral

Weak acid + Strong base Basic

Strong acid + Weak base Acidic

Thus, the solution containing a weak acid and a strong base will turn the colour of the phenolphthalein indicator to pink.

Suggest Corrections