Question

In order to bring initial chemical change in the ore, the process of heating of ore below its melting point is known as
A. Reduction
B. Smelting
C. Calcination
D. Roasting

Answer 1

Hint: Roasting is a process of preparing oxide ore from sulphide ore. This process occurs below the melting point of the sulphide ore.

Complete Step by Step Answer:
Roasting is defined as a process of heating a sulphide ore below the temperature of the melting point of the ore and in the presence of air. This process occurs at high temperatures. This process brings a chemical change to the ore by the conversion of the sulphide ore to oxide.

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 D.

Additional Information: 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.

Note: The reaction occurs below the melting point as above the melting point the sulphide ore will melt and we will not get the desired product that is oxide ore.