Sulphide ore on roasting gives a gas $X$. $X$ reacts with $Cl_{2}$ in the presence of activated charcoal to give $Y$. $Y$ is

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

Which one of the following statements is false?

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

Which of the following is an example of the calcination process?