Ice at $-20\,^{\circ}C$ is added to $50\,g$ of water at $40\,^{\circ}C.$ When the temperature of the mixture reaches $0\,^{\circ}C,$ it is found that $20\,g$ of ice is still unmelted. The amount of ice added to the water was close to ........$g$ (Specific heat of ice $= 2.1\,J/g/^{\circ}C,$ Specific heat of water $= 4.2\,J/g/^{\circ}C,$ Heat of fusion of water at $0\,^{\circ}C = 334\,J/g).$

$100 \, g$ of ice at $0^{\circ}C$ is mixed with $100 \, g$ of water at $100^{\circ}C$. What will be the final temperature of the mixture in $^{\circ}C$?

The temperatures of two liquids $A$ and $B$ are $32 \, ^\circ C$ and $24 \, ^\circ C$ respectively. When equal masses of both are mixed,the temperature of the mixture becomes $28 \, ^\circ C$. The ratio of their specific heats is .....

$A$ piece of copper of mass $250 \ g$ at $500^{\circ} C$ is put inside a calorimeter of water equivalent $50 \ g$ containing $200 \ g$ of water at $20^{\circ} C$. At thermal equilibrium,the temperature of the mixture is $60^{\circ} C$. The specific heat of copper (in $J / kg \cdot ^{\circ} C$) is approximately: [Specific heat of water $= 4200 \ J / kg \cdot ^{\circ} C$]

$A$ $10 \,kW$ drilling machine is used to drill a bore in an aluminium block of mass $25 \,kg$. If the machine is on for $3 \,minutes$ and $50 \%$ of the heat liberated is absorbed by the block, what is the rise in temperature of the block (in $^{\circ} C$)? (Specific heat of aluminium is $900 \,J \,kg^{-1} \,K^{-1}$)

Steam at $100^{\circ} C$ is passed into $1 \, kg$ of water contained in a calorimeter at $9^{\circ} C$ until the temperature of the water and calorimeter increases to $90^{\circ} C$. The mass of the steam condensed is nearly (water equivalent of calorimeter $= 0.1 \, kg$, specific heat of water $= 1 \, cal \cdot g^{-1} \cdot {}^{\circ} C^{-1}$, and latent heat of vaporisation $= 540 \, cal \cdot g^{-1}$). (in $g$)