A water heater of power $2000\,W$ is used to heat water. The specific heat capacity of water is $4200\,J\,kg ^{-1}\, K ^{-1}$. The efficiency of heater is $70 \%$. Time required to heat $2\,kg$ of water from $10^{\circ}\,C$ to $60^{\circ}\,C$ is $……….s$. (Assume that the specific heat capacity of water remains constant over the temperature range of the water).

$5\, g$ of ice at $0°C$ is dropped in a beaker containing $20\, g$ of water at $40°C.$ The final temperature will be…….. $^oC$

A copper ball of mass $100\ gm$ is at a temperature $T$. It is dropped in a copper calorimeter of mass $100\ gm$, filled with $170\  gm$ of water at room temperature. Subsequently, the temperature of the system is found to be $75^o C$. $T$ is given by……$^oC$ (Given : room temperature $= 30^o  C$, specific heat of copper $=$ $0.1$ $cal/gm^o C$)

A block of mass $2.5\,\, kg$ is heated to temperature of $500^o C$ and placed on a large ice block. ……… $kg$ is the maximum amount of ice that can melt (approx.). Specific heat for the body $= 0.1 Cal/gm^o C$.

A beaker contains $200\, gm$ of water. The heat capacity of the beaker is equal to that of $20\, gm$ of water. The initial temperature of water in the beaker is $20°C.$ If $440\, gm$ of hot water at $92°C$ is poured in it, the final temperature (neglecting radiation loss) will be nearest to…….. $^oC$