A thermally insulated vessel contains some water at $0^0C$. The vessel is connected to a vacuum pump to pump out water vapour. This results in some water getting frozen. It is given Latent heat of vaporization of water at $0^o C =21 × 10^5 J/kg$ and latent heat of freezing of water $= 3.36 × 10^5 J/kg$. The maximum percentage amount of water that will be solidified in this manner will be …… $\%$

Water is used to cool radiators of engines in car because

sphere of $0.047 \;kg$ aluminium is placed for sufficient time in a vessel containing boiling water, so that the sphere is at $100\,^{\circ} C .$ It is then immediately transfered to $0.14 \;kg$ copper calorimeter containing $0.25\; kg$ water at $20\,^{\circ} C$. The temperature of water rises and attains a steady state at $23\,^{\circ} C$. Calculate the specific heat capacity of aluminium in $kJ\;kg^{-1} K^{-1}$ 

A block of ice at $-20\,^oC$ having a mass of $2\, kg$ is added to a $3\, kg$ water at $15\,^oC$. Neglecting heat losses and the heat capacity of the container

The heat required to change $1 \,kg$ of ice at $-8^{\circ} C$ into water at $20^{\circ} C$. at $1 \,atm$ of pressure, is closest to ………….$\,kJ$ (Assume that ice has a specific heat capacity $2.1 \,kJ / kg / K$. water has a specific heat capacity $4.2 \,kJ / kg / K$, and latent heat of fusion of ice is $333 \,kJ / kg$ )