CAPF AC 2022 Q36: Science & Technology – Chemistry
Cinnabar is an ore of
- (a) mercury
- (b) zinc
- (c) copper
- (d) lead
Answer: (a) mercury
Explanation
Cinnabar
How to think: cinnabar is the bright red ore of mercury.
Its chemical name is mercury(II) sulphide, HgS.
NCERT uses it as the example of a metal low in the activity series.
| Metal | Chief ore | Formula |
|---|---|---|
| Mercury | Cinnabar | HgS |
| Zinc | Zinc blende, calamine | ZnS, ZnCO3 |
| Copper | Copper pyrites, copper glance | CuFeS2, Cu2S |
| Lead | Galena | PbS |
| Aluminium | Bauxite | Al2O3.2H2O |
How mercury is got from it: cinnabar is heated in air.
It first forms mercuric oxide, which on further heating gives mercury.
Answer: (a) mercury.
Why each option is right or wrong
- (a) CORRECT. Cinnabar (HgS) is the chief ore of mercury.
- (b) Incorrect. The ores of zinc are zinc blende and calamine.
- (c) Incorrect. The ores of copper are copper pyrites and copper glance.
- (d) Incorrect. The chief ore of lead is galena.
Key point
Cinnabar HgS → mercury. Galena PbS → lead. Zinc blende ZnS and calamine ZnCO3 → zinc. Copper pyrites CuFeS2 → copper. Bauxite → aluminium. Haematite and magnetite → iron.
Remember
Cinnabar (HgS) is the ore of mercury.
Common mistakes
- Mixing up cinnabar (mercury) with calamine (zinc).
- Confusing cinnabar with galena, the sulphide ore of lead.
- Thinking mercury, being a liquid, has no solid ore.
Exam tip
Educated guess: NCERT's one worked example of roasting a sulphide ore of a least reactive metal is cinnabar giving mercury.
Sources
- NCERT Class X Science — Metals and Non-metals (extracting metals low in the activity series)
- NCERT Class XII Chemistry — General Principles and Processes of Isolation of Elements