Water falls from a height of $500\,m$. The rise in temperature of the water at the bottom,assuming all energy remains in the water,will be ........ $^oC$ [Specific heat of water = $4.2\,kJ/kg\cdot K$]

$A$ calorimeter of mass $0.2 \ kg$ and specific heat $900 \ J/kg \cdot K$ contains $0.5 \ kg$ of a liquid of specific heat $2400 \ J/kg \cdot K$. Its temperature falls from $60^{\circ}C$ to $55^{\circ}C$ in one minute. The rate of cooling is ....... $J/s$.

$A$ geyser heats water flowing at a rate of $2.0 \; kg$ per minute from $30^{\circ} C$ to $70^{\circ} C$. If the geyser operates on a gas burner,the rate of combustion of fuel will be $\dots \; g \min^{-1}$.
[Heat of combustion $= 8 \times 10^{3} \; J \cdot g^{-1}$,Specific heat of water $= 4.2 \; J \cdot g^{-1} \cdot {}^{\circ} C^{-1}$]

Find the difference in temperature between the water at the top and the bottom of a $20 \ m$ high waterfall, assuming $10 \%$ of the energy of the fall is spent in heating the water. [Use specific heat capacity of water $= 4000 \ J \ kg^{-1} K^{-1}$ and $g = 10 \ m/s^2$]. (in $^{\circ} C$)

Work done in converting $1 \, g$ of ice at $-10^{\circ} C$ into steam at $100^{\circ} C$ is .......... $kJ$.

$A$ calorimeter has a water equivalent of $5 \times 10^{-3} \ kg$ and contains $25 \times 10^{-3} \ kg$ of water. It takes $3 \ minutes$ to cool from $28^{\circ}C$ to $21^{\circ}C$. When it is filled with turpentine oil,it takes $2 \ minutes$ to cool from $28^{\circ}C$ to $21^{\circ}C$. The specific heat of turpentine oil is ..... $cal/g^{\circ}C$.