In metallurgy,calcination is used for ...... .

$A$ metal obtained directly by roasting of its sulphide ore is

$A$ reverberatory furnace is employed in the metallurgical process mainly for

The chemical reaction that involves the roasting process 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

Given below are two statements:
Statement-$I$ : In the metallurgy process,sulphide ore is converted to oxide before reduction.
Statement-$II$ : Oxide ores in general are easier to reduce.
In the light of the above statements,choose the most appropriate answer from the options given below :