Sulphur is a versatile element that can exhibit different oxidation states in various compounds. The oxidation state of sulphur in S2O can be either -2 or +4, depending on the specific compound and its chemical environment. Let's explore the reasons behind these two oxidation states in detail.

1. Oxidation state of -2:
- In S2O, the oxidation state of sulphur is -2. This means that each sulphur atom contributes two electrons towards the overall charge of the compound.
- Sulphur typically forms covalent bonds with other elements, and in S2O, both sulphur atoms are bonded together by a single covalent bond.
- The electronegativity of sulphur is lower than oxygen, so the oxygen atoms tend to attract the shared electrons more strongly, resulting in a partial negative charge on the oxygen atoms and a partial positive charge on the sulphur atoms.
- Since there are two oxygen atoms attached to each sulphur atom, the overall charge contributed by the sulphur atoms is -2.

2. Oxidation state of +4:
- In some compounds, such as sulfur dioxide (SO2) and sulphuric acid (H2SO4), sulphur can have an oxidation state of +4.
- In SO2, sulphur forms a double bond with one oxygen atom and a single bond with another oxygen atom. The electronegativity difference between sulphur and oxygen causes the oxygen atoms to attract the shared electrons more strongly, resulting in a partial negative charge on the oxygen atoms and a partial positive charge on the sulphur atom. Thus, sulphur has an oxidation state of +4.
- In H2SO4, sulphur forms two double bonds with oxygen atoms and two single bonds with other oxygen atoms. Again, the electronegativity difference leads to a partial positive charge on sulphur, giving it an oxidation state of +4.

In summary, the oxidation state of sulphur in S2O can be either -2 or +4, depending on the compound. In S2O, the oxidation state is -2 due to the electronegativity difference between sulphur and oxygen. In compounds like SO2 and H2SO4, the oxidation state of sulphur is +4 because of the formation of double bonds with oxygen atoms.