What happens to the total entropy of the system and surroundings during a spontaneous irreversible process?

At the boiling point of water,$900 \ J/g$ of heat is exchanged. What is the increase in entropy in $J \ K^{-1} \ mol^{-1}$?

For which one of the following reactions, the entropy change is positive?

The entropy change involved in the conversion of $1 \, \text{mole}$ of liquid water at $373 \, K$ to vapour at the same temperature will be $[\Delta H_{vap} = 2.257 \, kJ/g]$. (in $, kJ/K$)

For the reaction $MgCO_3(s) \rightarrow MgO(s) + CO_2(g)$,the value of $\Delta S$ is:

Which one of the following involves a decrease in entropy?