Why is iron pyrite not the ideal choice of ore for the extraction of iron?

In the extraction of iron from hematite,what is the role of limestone?

Which of the following factors is of $\text{no significance}$ for roasting sulphide ores to the oxides and not subjecting the sulphide ores to carbon reduction directly?

Write the chemical reactions taking place in the extraction of zinc from zinc blende.

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

Why are sulphide ores converted to oxide before reduction?