Question

The process of roasting of an ore is carried out in the
(A) Absence of air
(B) Presence of air
(C) Limited supply of air
(D) None of the above

Answer 1

Hint: The process of roasting has many advantages. The substances that have been roasted can easily be powdered. It is a very quick method and requires very little fat. The content of moisture in the substances that have been roasted, gets reduced. It also has many disadvantages. Sulphide-based roasting is a major source of air pollution, and it has the further disadvantage of releasing great amounts of acidic, poisonous, and metallic chemicals into the environment.

Complete Step by Step Answer:
In the metallurgical process of roasting, ore is heated below its melting point in the presence of excess air and converted into its oxide. In metallurgical processes, when ores are transformed into oxides and then metals are extracted, roasting is used.

Volatile substances, moisture, and impurities are all eliminated throughout this process. There is no dehydration step in the roasting process. An example of a roasting process is the conversion of zinc sulphide into zinc oxide in the presence of an excess of air at 1200K.
$2ZnS+3O_2 \rightarrow 2ZnO + 2SO_2$
Correct Option: (B) Presence of air.

Note: Typically, roasting is carried out to ensure that the desired chemical reaction begins slowly, continues for a sufficient amount of time to transform enough of the product's chemicals into the desirable material, and then ends. Roasting is an exothermic process.