Question

Roasting is generally done in case of the following
A. Oxide ores
B. Silicate ores
C. Sulphide ores
D. Carbonate ores

Answer 1

Hint: Roasting is a process of preparing oxide ore. In this process sulphide ores are generally used. Heating of sulphide ores gives oxide ore.

Complete Step by Step Answer:
Roasting is defined as a process of heating a sulphide ore in a high temperature and in the presence of air. It is a step in the processing of certain oxide ores. More specifically, the process of roasting often involves gas–solid reactions at a certain temperature to purify metal components.

Roasting involves thermal gas–solid reactions, which are generally oxidation, reduction, chlorination, sulfation, and pyrohydrolysis. In the process of roasting, the ore is treated with very hot air. This process is applied to sulphide ores. The sulphide is converted to an oxide ore, and sulphur is converted to sulphur dioxide.

The reaction can be given as follows:
$2ZnS+3{{O}_{2}}\to 2ZnO+2S{{O}_{2}}$
Thus in this reaction two moles of zinc sulphide react with three moles of oxygen gas to produce two moles of zinc oxide along with two moles of sulphur dioxide gas.
Thus the correct option is C.

Note: The gaseous product of roasting or sulphide roasting that is sulphur dioxide is often used to produce a strong acid that is sulphuric acid. Many sulphide ores contain other components like arsenic that are released to the environment.