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Skating on ice is possible because

  • A.The surface of ice is smooth
  • B.Ice is cold
  • C.The pressure on the ice due to skate melts the ice by lowering its melting point forming a thin film of water
  • D.The pressure on the ice due to skate raises its melting point

Answer: C

Because the pressure of the skate melts the ice by lowering its melting point.

Water is unusual in expanding when it freezes, so pressure favours the denser liquid phase and the melting point falls. A thin film of water forms under the blade and acts as a lubricant, refreezing once the skate has passed.

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