Question

Match the conversions in List 1 with the type(s) of reaction(s) given in List 2. Indicate your answer by darkening the appropriate bubbles of the $4\times 4$ matrix given in the ORS.

Answer 1

Roasting is a step of the processing of certain ores. It is a metallurgical process involving gas–solid reactions at elevated temperatures with the goal of purifying the metal component(s).

$2PbS+3O_2\to 2PbO+2S{O}_2$

Calcination is also used to mean a thermal treatment process in the absence or limited supply of air or oxygen applied to ores and other solid materials to bring about a thermal decomposition, phase transition, or removal of a volatile fraction.

$CaC{O}_3\to CaO+C{O}_2$

Extraction
(1) Zinc blende is heated in air to get rid of the Sulphur and to convert it into ZnO which is more reactive. This way, it will be easier to obtain the zinc metal.
Reaction when Zinc Blende is heated in the air:

$2ZnS+3O_2\to 2ZnO+2S{O}_2$

(2) The Zinc Oxide is then mixed with crushed coke (carbon) and heated at 1673 K in fire clay retorts (Belgian Process) when ZnO gets reduced to metallic zinc. In this reaction, carbon acts as the reducing agent as Zinc's oxidation state is reduced from +2 to 0 and carbon itself is reduced.

Reaction when Zinc Oxide is heated in fire clay retorts:

$2ZnO+C\to 2Zn+C{O}_2$

Self reduction process: This process is also called autoreduction process or air reduction process. The sulphide ores of less electropositive metals like Hg, Pb, Cu etc., are heated in air as to convert part of the ore into oxide or sulphate which then reacts with the remaining sulphide ore to give the metal and sulphur dioxide. No external reducing agent is used in this process.

$2C{u}_{2}S+3O_2\to C{u}_{2}O+2S{O}_2$

Hence, $A-1:B-2:C-1,3:D-1,4$