WBCS.LIVE practice question

What is the primary reason why a needle floats on the surface of clean water?

Solve this multiple-choice question and check the correct answer with its explanation below.

Answer options

  1. Viscosity of water
  2. Buoyant force
  3. Surface tension
  4. Low density of steel

Correct answer and explanation

Correct answer: Surface tension

Explanation: āœ… Correct Answer: C) Surface tension šŸ“š Explanation: Surface tension is a property of liquids that makes their surface act like a thin, elastic membrane. When a small needle is placed carefully on water, the cohesive forces between water molecules create enough upward tension to support its weight. If soap or detergent is added, the surface tension breaks and the needle immediately sinks.