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Question:

What change will you observe if you test soap with litmus paper (red and blue)?

Solution:

Soap is basic in nature (alkaline). When you test soap with litmus paper:

  • Red litmus paper will turn blue. This is because red litmus paper turns blue in the presence of a base or alkali.
  • Blue litmus paper will remain blue. Blue litmus paper only changes color in the presence of an acid; it remains blue in a neutral or alkaline solution.