What happens when
(i) Concentrated `H_2 SO_4` is added to calcium fluoride.
(ii) `SO_3` is passed through water ?

Explanation

To solve the question, we will analyze both parts separately.

### Part (i): Concentrated `H2SO4` and Calcium Fluoride

1. **Identify the Reactants**: The reactants in this case are concentrated sulfuric acid (`H2SO4`) and calcium fluoride (`CaF2`).

2. **Write the Reaction**: When concentrated sulfuric acid is added to calcium fluoride, a chemical reaction occurs. The products of this reaction are calcium sulfate (`CaSO4`), hydrofluoric acid (`HF`), and possibly other fluorine compounds.

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