Why is water used in a rubber bag for fomentation on the body?

The molar mass of a substance is $50 \, g/mol$. When $300 \, J$ of heat is supplied to a $25 \, g$ sample of this substance,its temperature increases from $30^{\circ}C$ to $50^{\circ}C$. The value of its molar heat capacity is ..... $J/mol \cdot ^{\circ}C$.

$A$ $10\, kW$ drilling machine is used to drill a bore in a small aluminium block of mass $8.0\, kg$. How much is the rise in temperature of the block in $2.5$ minutes,assuming $50\, \%$ of power is used up in heating the machine itself or lost to the surroundings? (Specific heat of aluminium $= 0.91\, J\, g^{-1}\, K^{-1}$)

$A$ heater supplying constant power $P$ watts is switched $ON$ at time $t=0$ to raise the temperature of a liquid kept in a calorimeter of negligible heat capacity. $A$ student records the temperature of the liquid $T(t)$ at equal time intervals. $A$ graph is plotted with $T(t)$ on the $Y$-axis versus $t$ on the $X$-axis. Assume that there is no heat loss to the surroundings during heating. Then,

Define molar specific heat and state its $SI$ unit.

What is the heat capacity of copper of $40 \, g$ and specific heat $0.3 \, erg \, g^{-1} (^{\circ} C)^{-1}$?