JEE Main 2021 · 25 July · evening · Single correct · +4 / −1
Match List I with List II : (Both having metallurgical terms)
Choose the correct answer from the options given below :
| 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 |
- (a) (a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)
- (b) (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
- (c) (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)
- (d) (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
Answer and solution
Answer (a) (a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)
Solution
Chemistry ma’am · 3 steps
Lock in the sure pairs first, silver with cyanide and froth floatation with sulfides; the rest falls in.
- Sure matches first. Silver is concentrated by leaching with dilute NaCN solution, which forms soluble [Ag(CN)₂]⁻. Froth floatation works on sulfide ores, because pine oil wets sulfide particles and carries them up in the froth.
- Iron and copper. The blast furnace reduces iron oxide with coke and gives pig iron, about 4% carbon. Copper ore is heated with silica in a reverberatory furnace to make matte, and the matte then gives blister copper, so (c) pairs with (i).
List I Matches Reason (a) Concentration of Ag ore (iii) Leaching with dilute NaCN Ag dissolves as [Ag(CN)₂]⁻ (b) Blast furnace (ii) Pig iron Coke reduces iron oxide (c) Blister copper (i) Reverberatory furnace Copper matte is made in this furnace (d) Froth floatation method (iv) Sulfide ores Oil wets sulfide particles - So. The matching is (a)-(iii), (b)-(ii), (c)-(i), (d)-(iv), which is option (a).
The idea to keep. In metallurgy matching, lock in the textbook pairs first: cyanide leaching for Ag and Au, froth floatation for sulfides, blast furnace for pig iron. Then the remaining pair comes by elimination.
Answer from the NTA final answer key. Solution by PrepWiser.