Match List I with List II.
|
LIST I |
LIST II |
|
A. Sulphide ore |
I. Silver |
|
B. Mond's process |
II. Nickel |
|
C. Cupellation |
III. Carbonate ores |
|
D. Calcination |
IV. Froth floatation |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A-IV, B-II, C-I, D-III
Extracting a metal involves concentrating the ore, converting it to the oxide (by calcination or roasting), reducing the oxide to the metal and finally refining the metal. Each item of List I belongs to one stage and one kind of ore or metal.
A. Sulphide ore — This matches IV. Froth floatation. The powdered ore is mixed with water, pine oil (collector) and a froth stabiliser; the sulphide particles are wetted by the oil and rise with the froth, while the gangue, wetted by water, settles.
B. Mond’s process — This matches II. Nickel. Impure nickel is heated in carbon monoxide to form volatile nickel tetracarbonyl, which is decomposed at a higher temperature to give pure nickel.
\( \displaystyle \ce{Ni + 4CO} \xrightarrow{\text{330-350 K}} \ce{Ni(CO)4} \xrightarrow{\text{450-470 K}} \ce{Ni + 4CO} \)
C. Cupellation — This matches I. Silver. Impure silver containing lead is heated in air in a porous dish (cupel); lead is oxidised to litharge, PbO, which is absorbed by the cupel or blown away, and pure silver is left behind.
\( \ce{2Pb + O2 -> 2PbO} \)
D. Calcination — This matches III. Carbonate ores. Heating the ore drives off volatile matter such as \( \ce{CO2} \), leaving the metal oxide.
\( \ce{ZnCO3(s) -> ZnO(s) + CO2(g)} \)
Shortcut: A-IV (froth floatation for sulphide ores) appears only in Option (3).
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.