During which of the following processes is an ore converted into its oxide?

Roasting of sulphides gives the gas $X$ as a byproduct. This is a colourless gas with a choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic,acts as a reducing agent,and its acid has never been isolated.
The gas $X$ is

Roasting is done in

Consider two chemical reactions $(A)$ and $(B)$ that take place during metallurgical processes:
$(A)$ $ZnCO_{3(s)} \longrightarrow ZnO_{(s)} + CO_{2(g)}$
$(B)$ $2ZnS_{(s)} + 3O_{2(g)} \longrightarrow 2ZnO_{(s)} + 2SO_{2(g)}$
The correct names for these processes are:

The chemical reaction that involves the roasting process is:

Which reaction is not possible for calcination?