Question

Select the correct statements regarding the roasting process.
(I) It is the process of heating ore in air to obtain the oxide.
(II) It is an exothermic process.
(III) It is used for hydrated oxide and oxysalt ore.
(IV) It is used after the concentration of ore.
(A) I, II and III
(B) I, II and IV
(C) I, III and IV
(D) I, II, III and IV

Answer 1

To solve this we must know that roasting is a metallurgical process which is used for purifying the metals. In roasting, the ores of metals or the concentrated ores are heated at high temperature. The ores are heated in presence of air. Roasting is generally done for sulphide ores.

Complete step-by-step answer : We know that roasting is a metallurgical process which is used for purifying the metals. The process of heating of ore to a high temperature in presence of air is known as roasting.
Thus, the statement ‘it is the process of heating ore in air to obtain the oxide’ is correct.

During roasting, a large amount of acidic, metallic and other toxic compounds are released. Thus, roasting is an exothermic process.
Thus, the statement ‘it is an exothermic process’ is correct.

The process of roasting is generally applied to sulphide minerals. During roasting, sulphide is converted to an oxide and sulphur dioxide gas is released.
Thus, the statement ‘it is used for hydrated oxide and oxysalt ore’ is not correct.

First the ore is concentrated. During concentration of the ore, the impurities are removed. The concentrated ore is then roasted to convert it to oxide.
Thus, the statement ‘it is used after the concentration of ore’ is correct.

Thus, the statements I, II and IV are correct.

Thus, the correct statement is (B) I, II and IV.

Note: Roasting consists of gas-solid reactions which include oxidation, reduction, chlorination, sulphation and pyrohydrolysis. During roasting a large amount of acidic, metallic and other toxic compounds are released in the atmosphere. Thus, roasting is a source of air pollution.