Consider the following observations:

1. NiCl2 readily dissolves in water to give a green solution. It dissolves more slowly in ethanol to give a blue solution. It is insoluble in hexane (C6H14).

2. When the water solution, assumed to be in the form [Ni(OH2)6]2+, is treated with ethanol, no color change is observed. However, when the ethanol solution is treated with water, the color of the solution quickly becomes lighter.

3. When a small quantity of KCN is added to either the ethanol or water solution, the solution rapidly turns a deep blue color.

Based on these observations, which is the correct order of these ligands in terms of highest to lowest (decreasing) Lewis basicity?

1. KCN - H2O - ethanol - hexane
2. ethanol - KCN - H2O - hexane
3. ethanol - hexane - KCN - H2O
4. hexane - ethanol - H2O - KCN
5. KCN - ethanol - hexane - H2O
6. H2O - KCN - ethanol - hexane
7. H2O - KCN - hexane - ethanol