For a $Carnot$ engine,the source is at $500 \ K$ and the sink at $300 \ K$. What is the efficiency of this engine?

The unit of entropy is

The molar heat of vaporisation of a liquid is $6 \ kJ \ mol^{-1}$. If the entropy change is $16 \ J \ mol^{-1} \ K^{-1}$,the boiling point of the liquid is:

Identify the reaction/process in which the entropy increases.

The enthalpy change for the transition of liquid water to steam at $100\,^oC$ is $40.8\, kJ\, mol^{-1}$. The entropy change for this process is .... $J\, K^{-1}\, mol^{-1}$.

What happens to the entropy during the melting of ice to water?