Which has the greatest entropy?

0.75 M MgCl2(aq)

1.0 L H20(l)

3.2 M N2(aq)

3.4 M O2(aq)

1.2 M O2(aq)

The substance with the greatest entropy is 1.0 L H2O(l) since it is in the liquid state. In general, substances in the liquid state have higher entropy compared to substances in the solid or aqueous state.