Question

$200g$ of ice at $0^{\circ }C$ converts into water at $0^{\circ }C$ in 1 minute when heat is supplied to it at a constant rate. In how much time $200g$ of water at $0^{\circ }C$ will change to ${20}^{\circ }C$ ? Take specific latent heat of ice = $336J{g}^{-1}$

• A. $5s$
• B. $10s$
• C. $15s$
• D. $30s$

Answer 1

Answer: (C)

$15s$

Heat supplied to melt ice $Q=200\times 336=67200J$

this heat is supplied in $t=60sec$

rate of heat supply=$\frac{67200}{60}=1120J/s$

heat required to raise temperature by ${11}^{o}C$

$Q_1=200\times 4.2\times 20=16800J$

times required =$\frac{16800}{1120}=15s$