Match List I with List II
|
LIST I |
LIST II |
| A. Zone refining | I. Aluminium |
| B. Blast furnace | II. Iron |
| C. Froth floatation process | III. metal sulphides |
| D. Hall-Heroult process | IV. Germanium |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A-IV, B-II, C-III, D-I
Each step of metallurgy uses a method suited to the ore or the metal: concentration of the ore (froth flotation), reduction to the metal (blast furnace, electrolysis) and refining (zone refining).
(A) Zone refining — This matches (IV) Germanium. Impurities are more soluble in the melt than in the solid metal; a moving heater sweeps them to one end. It gives metals of very high purity such as germanium, silicon, boron, gallium and indium (semiconductors).
(B) Blast furnace — This matches (II) Iron. Iron oxides, mixed with limestone and coke, are reduced by carbon monoxide in the blast furnace:
\( \ce{Fe2O3 + 3CO -> 2Fe + 3CO2} \)
(C) Froth floatation process — This matches (III) metal sulphides. It removes gangue from sulphide ores: the sulphide particles are wetted by oil (collector, e.g. pine oil) and rise with the froth, while the gangue is wetted by water and sinks.
(D) Hall-Heroult process — This matches (I) Aluminium. Purified \( \ce{Al2O3} \) mixed with \( \ce{Na3AlF6} \) (cryolite) or \( \ce{CaF2} \) is electrolysed; aluminium is liberated at the cathode:
\( \displaystyle \text{Cathode: }\ce{Al^3+(melt) + 3e- -> Al(l)} \)
\( \displaystyle \text{Anode: }\ce{C(s) + O^2-(melt) -> CO(g) + 2e-},\quad \ce{C(s) + 2O^2-(melt) -> CO2(g) + 4e-} \)
\( \displaystyle \text{Net: }\ce{2Al2O3 + 3C -> 4Al + 3CO2} \)
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.