$A$ 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 $= 4.2 \; J \cdot g^{-1} \cdot {}^{\circ} C^{-1}$]

$A$ continuous flow water heater (geyser) has an electrical power rating $= 2 \, kW$ and efficiency of conversion of electrical power into heat $= 80 \%$. If water is flowing through the device at the rate of $100 \, cc/sec$,and the inlet temperature is $10^{\circ} C$,the outlet temperature will be ....... $^{\circ} C$.

$500\, g$ of water and $100\, g$ of ice at $0\,^{\circ}C$ are in a calorimeter whose water equivalent is $40\, g$. $10\, g$ of steam at $100\,^{\circ}C$ is added to it. Then the final amount of water in the calorimeter is ....... $g$ (Latent heat of ice $= 80\, cal/g$,Latent heat of steam $= 540\, cal/g$).

$A$ piece of ice falls from a height $h$ so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of $h$ is (Latent heat of ice is $L = 3.4 \times 10^{5} \text{ J/kg}$ and $g = 10 \text{ N/kg}$) (in $\text{ km}$)

How much energy will be released by cooling $1\,kg$ of water up to a temperature of $10\,^{\circ}C$?

Fill in the blanks:
$1.$ The temperature of freezing point ...... and temperature of boiling point ...... are taken in a Fahrenheit thermometer.
$2.$ The zeroth law of thermodynamics defines ...... and the first law of thermodynamics defines ......
$3.$ At ...... temperature,water and water vapour have equal density.
$4.$ The ...... has the maximum value of specific heat.