Roasting is a process in which the ore (mostly sulphide) is heated strongly in the presence of excess of air. The heating should be done at a temperature below the melting point of the ore.
Select of correct statement :

Options

A. Roasting removes easily oxidisable volatile impurities like arsenic as `As_(2) O_(3)`, antimony as `Sb_(2) O_(3)`, and sulphur as `SO_(2)`.
B. The release of `SO_(2)` (in roasting process) has been a serious air pollution problem.
C. In roasting process, if temperature is fairly low (about `500^@ C`) and the concentration of `SO_(2)` in the gaseous enviourment is more, sulphate may be produced, that is stable, and high temperature is needed to decompose it.
D. All are correct

Answer

D

Explanation

All the options `a,b` and `c` are correct.