Statement (i): The oxidation state of sulphur in its compounds vary from -2 to 8.

Explanation:
The oxidation state of an element is a measure of the degree of oxidation or reduction of that element in a chemical compound. It represents the number of electrons that an atom of that element has gained or lost when forming a compound.

Sulphur can exhibit a variety of oxidation states in its compounds ranging from -2 to +6. However, there are a few exceptions where sulphur can have oxidation states beyond +6.

- In most of its compounds, sulphur has an oxidation state of -2. This is because it tends to gain two electrons to achieve a stable noble gas configuration, similar to the nearest noble gas, argon.

- In some compounds, such as sulphur dioxide (SO2) and sulphur trioxide (SO3), sulphur exhibits an oxidation state of +4 and +6, respectively. In these cases, sulphur forms multiple bonds with oxygen, resulting in a higher oxidation state.

- In a few rare cases, sulphur can have oxidation states beyond +6. For example, in sulfuric acid (H2SO5), sulphur has an oxidation state of +8. This is achieved by forming multiple bonds with oxygen atoms.

Therefore, the statement (i) is incorrect as the oxidation state of sulphur in its compounds can vary from -2 to +8, not just from -2 to 8.

Statement (ii): Tetrahalides of the 16th group have a see-saw shape.

Explanation:
The 16th group of elements in the periodic table is also known as the chalcogens. This group includes elements such as oxygen (O), sulphur (S), selenium (Se), and tellurium (Te).

Tetrahalides of these elements, such as sulfur tetrafluoride (SF4) and selenium tetrafluoride (SeF4), do not have a see-saw shape. Instead, they have a trigonal bipyramidal shape.

In a trigonal bipyramidal shape, there are three equatorial atoms and two axial atoms. The equatorial atoms are located in the same plane, while the axial atoms are above and below this plane. This geometry is observed in molecules with a central atom surrounded by five electron pairs, where three of the electron pairs are in the equatorial plane, and the other two are in the axial positions.

On the other hand, a see-saw shape is observed in molecules with a central atom surrounded by five electron pairs, where four of the electron pairs are in the equatorial plane, and the fifth electron pair is in an axial position. This geometry is not observed in the tetrahalides of the 16th group elements.

Therefore, the statement (ii) is incorrect as the tetrahalides of the 16th group do not have a see-saw shape.