Work done in converting one gram of ice at $-10^{\circ}C$ into steam at $100^{\circ}C$ is ....... $J$

$A$ copper block of mass $2.5\; kg$ is heated in a furnace to a temperature of $500\; ^{\circ}C$ and then placed on a large ice block. What is the maximum amount of ice (in $kg$) that can melt? (Specific heat of copper $= 0.39\; J\; g^{-1}\; K^{-1}$; heat of fusion of water $= 335\; J\; g^{-1}$)

$Assertion :$ In the pressure-temperature $(P-T)$ phase diagram of water,the slope of the melting curve is found to be negative.
$Reason :$ Ice contracts on melting to water.

$A$ geyser heats water flowing at the rate of $3.0 \, L/min$ from $27 \, ^{\circ}C$ to $77 \, ^{\circ}C$. If the geyser operates on a gas burner,what is the rate of consumption (in $g/min$) of the fuel if its heat of combustion is $4.0 \times 10^{4} \, J/g$?

Which form of heat was believed in before the modern time?

The temperature of Bhakhra dam water at the ground level with respect to the temperature at a high level should be: