How much heat energy is supplied when 5 kg of water at $20^{\circ} \mathrm{C}$ is brought to its boiling point? (Assume, specific heat of water $=4.2 \mathrm{~J} / \mathrm{g}^{\circ} \mathrm{C}$ )

What is the name of ideal-gas process in which no heat is transferred?

Mean free path of molecules in a polyatomic gas is independent of

A sheet of steel at $20^{\circ} \mathrm{C}$ has size as shown in figure below. If the co-efficient of linear expansion for steel is $10^{-5}{ }^{\circ} \mathrm{C}^{-1}$, then what is the change in the area at $60^{\circ} \mathrm{C}$ ?