100 W heater is used to melt 50 g of ice at 0°C. How long should the heater be switched on? (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
First, calculate the total heat needed: Q = mL = (50 g) × (334J/g) = 16,700 J. The heater provides power (P) of 100 W, which is 100 J/s. Time required is t = Q/P = 16,700J/100J/s=167seconds. Converting to minutes: 167 s / 60 s/min ≈2.8 minutes.
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