100 W heater is used to melt 50 g of ice at OC. 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
To melt 50 g of ice at 0°C, we need to supply energy equal to:Q = m × Lf where Q is the heat energy, m is the mass of ice, and Lf is the specific latent heat of the fusion of ice. Substituting the given values, we get: Q = 50 g × 334 J/g Q = 16700 J Now, the power of the heater is given as 100 W, which means that it can supply 100 J of energy every second. Therefore, the time required to supply 16700 J of energy is: t = Q/P t = 16700 J / 100 W t = 167 seconds t= 2.8 min Mathematically other options are incorrect
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