When $1\, kg$ of ice at $0^\circ C$ melts to water at $0^\circ C,$ the resulting change in its entropy,taking latent heat of ice to be $80\, cal/g,$ is ...... $cal/K$.

Why is a heat engine never $100\%$ efficient?

Which limitation of a heat engine is imposed by the second law of thermodynamics?

"Heat cannot flow by itself from a body at a lower temperature to a body at a higher temperature". This statement corresponds to:

An ideal gas in a cylinder is separated by a piston in such a way that the entropy of one part is $S_{1}$ and that of the other part is $S_{2}$. Given that $S_{1} > S_{2}$. If the piston is removed,then the total entropy of the system will be:

$A$ solid body of constant heat capacity $1 \ J/^oC$ is being heated by keeping it in contact with reservoirs in two ways :
$(i)$ Sequentially keeping in contact with $2$ reservoirs such that each reservoir supplies same amount of heat.
$(ii)$ Sequentially keeping in contact with $8$ reservoirs such that each reservoir supplies same amount of heat.
In both the cases,the body is brought from initial temperature $100^oC$ to final temperature $200^oC$. The entropy change of the body in the two cases respectively is :