Draw the temperature versus heat graph for heating of ice. Describe the phase change of the water on the basis of the graph. Explain the terms specific latent heat of fusion and specific latent heat of vaporization.

A steam engine intakes $50 \mathrm{g}$ of steam at $100°\mathrm{C}$ per minute and cools it down to $20°\mathrm{C}$. If latent heat of vaporization of steam is $540 \mathrm{cal} {\mathrm{g}}^{-1}$, then the heat rejected by the steam engine per minute is _____ $\times {10}^3 \mathrm{cal}$

(Given : specific heat capacity of water : $1 \mathrm{cal} {\mathrm{g}}^{-1}{{}^{\circ }\mathrm{C}}^{-1}$)

Heat required to melt $1 \mathrm{g}$ of ice is $80 \mathrm{cal}$. A man melts$60 \mathrm{g}$ of ice by chewing in one minute. His power is______

Explain the following temperature versus time graph:

A thermally insulated cubical box of side length $20 \mathrm{cm}$ and wall thickness $2 \mathrm{cm}$ containing $2 \mathrm{kg}$ of ice is closed on all sides. The mass of ice melted in $10$ hours is (Thermal conductivity of the material of the box $=0.01 {\mathrm{Wm}}^{-1} {\mathrm{K}}^{-1},$ latent heat of ice $=360\times {10}^3 \mathrm{J} {\mathrm{kg}}^{-1}$ and ambient temperature $=40 °\mathrm{C}$)