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NEET2008PhysicsMechanical Properties of FluidsActual

Assertion : A needle placed carefully on the surface of water may float, whereas a ball of the same material will always sink. Reason : The buoyancy of an object depends both on the material and shape of the object.

Options

  1. AIf both assertion and reason are true and reason is the correct explanation of assertion
  2. BIf both assertion and reason are true but reason is not the correct explanation of assertion
  3. CIf assertion is true but reason is false
  4. DIf both assertion and reason are false.

Correct answer

C. If assertion is true but reason is false

Step-by-step solution

A needle placed carefully on the surface of water may float due to surface tension as upward force due to surface tension balances the weight of the needle. But these upward force due to surface tension are very small as compared to weight of ball. Also the weight of liquid displaced by the ball immersed in liquid is less than the weight of the ball, hence ball sinks into the liquid.

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