$A$ 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 the heater is $70\%$. The 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).

Ice in a freezer is at $-7^{\circ} C$. $100 \, g$ of this ice is mixed with $200 \, g$ of water at $15^{\circ} C$. Take the freezing temperature of water to be $0^{\circ} C$,the specific heat of ice equal to $2.2 \, J/g^{\circ} C$,specific heat of water equal to $4.2 \, J/g^{\circ} C$,and the latent heat of ice equal to $335 \, J/g$. Assuming no loss of heat to the environment,the mass of ice in the final mixture is closest to .......... $g$.

$A$ sphere of $0.047 \; kg$ aluminium is placed for a sufficient time in a vessel containing boiling water,so that the sphere is at $100 \; ^{\circ}C$. It is then immediately transferred to a $0.14 \; kg$ copper calorimeter containing $0.25 \; kg$ water at $20 \; ^{\circ}C$. The temperature of the 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 mass $2.5 \ kg$ is heated to a temperature of $500^{\circ} C$ and placed on a large ice block. What is the maximum amount of ice (in $kg$) that can melt (approx.)? (Specific heat of the body $= 0.1 \ cal/g^{\circ} C$)

Steam at $100^{\circ}C$ is passed into a calorimeter containing $1\,kg$ of water with a water equivalent of $0.02\,kg$ at $15^{\circ}C$ until the temperature of the calorimeter rises to $80^{\circ}C$. The mass of the steam condensed is $.....\,kg$. (Given: $L = 536\,cal/g$,specific heat of water $c = 1\,cal/g^{\circ}C$)

Calorimeters are made of which of the following materials?