Multiple choice

Soap is used in washing because

  1. it increase the surface tension of water

  2. it lower the surface tension of water

  3. it lower the viscosity of water

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Soap acts as a surfactant, which lowers the surface tension of water, allowing it to penetrate fabrics and lift away dirt and grease more effectively.

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