Identify the correctly matched pair.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Calamine \(ZnCO_3\)
An ore is a mineral from which a metal can be extracted profitably. The common ores are oxides, carbonates and sulphides. Calamine is the carbonate ore of zinc, \( \ce{ZnCO3} \); it is turned into ZnO by calcination before reduction:
\( \displaystyle \ce{ZnCO3} \xrightarrow{\Delta} \ce{ZnO + CO2} \)
Why the other options are incorrect
Option (1) Bauxite \([Al_2 (OH)_4 Si_2O_5]\) — Incorrect. This is the formula of kaolinite (a form of clay); bauxite is AlOx(OH)3−2x, a hydrated aluminium oxide.
Option (2) Malachite \(Cu_2S\) — Incorrect. \( \ce{Cu2S} \) is copper glance; malachite is the basic carbonate \( \ce{CuCO3} \)·\( \ce{Cu(OH)2} \).
Option (4) Cuprite \(CuFeS_2\) — Incorrect. \( \ce{CuFeS2} \) is copper pyrites; cuprite is the oxide \( \ce{Cu2O} \).
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.
NCERT (Pre-rationalised edition, 2022-23):
Principal Ores of Some Important Metals (rows)
| Metal | Ores | Composition |
|---|---|---|
| Aluminium | Bauxite Kaolinite (a form of clay) | AlOx(OH)3–2x [where 0 < x < 1] [Al2(OH)4Si2O5] |
| Copper | Copper pyrites Malachite Cuprite Copper glance | CuFeS2 CuCO3.Cu(OH)2 Cu2O Cu2S |
| Zinc | Zinc blende or Sphalerite Calamine Zincite | ZnS ZnCO3 ZnO |