Match List I with List II: (Both having metallurgical terms)
List-I                                      List-II
(a) Concentration of Ag ore    (i) Reverberatory furnace
(b) Blast furnace                   (ii) Pig iron
(c) Blister copper                  (iii) Leaching with dilute NaCN solution
(d) Froth floatation method   (iv) Sulfide ores
Choose the correct answer from the options given below:

We begin by recalling the common metallurgical processes and the furnaces or techniques associated with them. We shall compare every item of List I with the most appropriate item of List II.

First, we look at item (a) of List I: “Concentration of Ag ore”. In metallurgy, silver (Ag) is frequently extracted from its ores such as argentite, $$Ag_{2}S$$, by the Mac-Arthur-Forrest cyanide process. In that process the ore is leached with a dilute aqueous solution of sodium cyanide, $$NaCN$$, which selectively dissolves silver according to the reaction

$$Ag_{2}S + 4NaCN \rightarrow 2Na[Ag(CN)2] + Na_{2}S.$$

Thus, concentration of Ag ore is correctly matched with “Leaching with dilute NaCN solution”, i.e. List-II item (iii).

Now we consider item (b) of List I: “Blast furnace”. A blast furnace is the tall shaft furnace used for the smelting of iron oxide ores. Inside the furnace, iron oxide is reduced to molten iron that contains about $$4\%$$ carbon and many other impurities. This impure molten iron solidifies to give what metallurgists call pig iron. Hence, the blast furnace is associated with “Pig iron”, i.e. List-II item (ii).

Next we move to item (c) of List I: “Blister copper”. Blister copper (so called because of its blister-like surface caused by escaping $$SO_{2}$$) is produced by melting copper matte in a reverberatory furnace. In this furnace, the charge is heated by hot gases which “reverberate” from the roof onto the ore, aiding oxidation of $$FeS$$ and $$Cu_{2}S$$ to yield almost pure copper. Therefore, blister copper matches with “Reverberatory furnace”, i.e. List-II item (i).

Finally we study item (d) of List I: “Froth flotation method”. The principle of froth flotation is based on the preferential wettability of ore and gangue particles. It is widely used for the concentration of sulphide ores such as $$ZnS$$, $$PbS$$, etc. Hence, “Froth flotation method” corresponds to “Sulfide ores”, i.e. List-II item (iv).

Collecting all the established matches, we have

$$\begin{aligned} (a) &\rightarrow (iii),\\ (b) &\rightarrow (ii),\\ (c) &\rightarrow (i),\\ (d) &\rightarrow (iv). \end{aligned}$$

Comparing this sequence with the options provided, we find that Option A exactly reproduces the same set of pairings.

Hence, the correct answer is Option A.