Identify the chemical formula of Bauxite.

Bauxite is the main ore of aluminum and primarily consists of hydrated aluminum oxide.
The chemical formula for Bauxite is $\boxed{\text{Al}_2\text{O}_3 \cdot \text{xH}_2\text{O}}$.

• Substance A: Aluminium reacts with $Fe_2O_3$ to produce $Fe + A$. This is a thermite reaction where aluminum reduces iron(III) oxide. $$2\text{Al} + \text{Fe}_2\text{O}_3 \longrightarrow \text{Al}_2\text{O}_3 + 2\text{Fe}$$ Therefore, A is aluminum oxide.
• Substance B: Aluminium reacts with $Cl_2$ to form B. Aluminium reacts with chlorine gas to form aluminum chloride. $$2\text{Al} + 3\text{Cl}_2 \longrightarrow 2\text{AlCl}_3$$ Therefore, B is aluminum chloride.
• Substance C: Aluminium reacts with Steam to form Gas C. Aluminium reacts with steam (hot water) to produce aluminum oxide and hydrogen gas. $$2\text{Al} + 3\text{H}_2\text{O(g)} \longrightarrow \text{Al}_2\text{O}_3 + 3\text{H}_2\text{(g)}$$ Therefore, C is hydrogen gas.

Cryolite ($Na_3AlF_6$) is used as a solvent for aluminum oxide ($Al_2O_3$) in the Hall-Héroult process. It significantly lowers the melting point of aluminum oxide from over $2000^\circ C$ to about $950^\circ C$, which reduces the energy consumption during electrolysis. It also enhances the electrical conductivity of the electrolyte.

For question 3, the table provides information about the reactions of metals S, T, and U. No specific questions are asked about this table.