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

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

Two moles of an ideal gas undergo free expansion from $10 \ L$ to $100 \ L$ at $300 \ K$. The values of $\Delta S_{system}$ and $\Delta S_{surroundings}$ are ($R$ is universal gas constant)

The entropy change for the expansion of $2 \, \text{mol}$ of an ideal gas from $2 \, \text{L}$ to $20 \, \text{L}$ at a temperature of $27 \, ^oC$ is ...... $(R = 2 \, \text{cal/mol K})$

The entropy of a sample of a certain substance increases by $0.836 \ J \ K^{-1}$ on adding reversibly $0.3344 \ J$ of heat at constant temperature. The temperature of the sample is.....$K$

The enthalpy of vaporisation of a certain liquid at its boiling point of $35^{\circ} C$ is $24.64 \ kJ \ mol^{-1}$. The value of change in entropy for the process is