For which of the following reactions will $\Delta S$ be maximum?

One mole of an ideal diatomic gas $(C_V = 5 \ cal)$ was transformed from initial $25 \ ^{\circ}C$ and $1 \ L$ to the state when temperature is $100 \ ^{\circ}C$ and volume $10 \ L$. The entropy change of the process can be expressed as $(R = 2 \ cal / mol \cdot K)$ :-

In which of the following processes is $\Delta S$ positive?

At $25\,^oC$ and $1\,atm$ pressure,mercury reacts with chlorine to form mercurous chloride: $2Hg + Cl_2 \to Hg_2Cl_2; \Delta H = -31.3\,kcal$. What is the entropy change of the reaction at $25\,^oC$?

What is the unit of $\Delta S_m^\circ$?

For a process to be spontaneous,the total entropy change of the system and its surroundings must be $ \Delta S_{total} > 0 $. This condition is characteristic of which type of process?