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A 100 W heater is used to melt 50g of ice at 0oC. How long should the heater be switched on? (The specific latent heat of fusion of ice is 334 J/g).

Correct answer: C. 2.8 min

  • A. 28 min
  • B. 16.7 min
  • C. 2.8 min
  • D. 167 min

Explanation

Given : Power = 100 watt Specific latent heat of fusion = L = 334 j/g M = 50 g Since we know that Q= ml Where Q is the heat energy ,thus the equation becomes ; Q= 50 x 334 Q = 16.7 kJ = 16700 J Now to find time we will use the formula ; Power = energy / time 100 = 16700 / t t = 167 seconds = 167/60 t = 2.78 = 2.8 minutes Thus only option C is correct

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