Metals are required for a variety of purposes. For this we need their extraction from their ores. Ores mined from the earth are usually contaminated with many impurities which must be removed prior to the extraction of metals. The extraction of pure metal involves the following steps :
(1) Concentration of ore
(2) Extraction of the metal from the concentrated ore
(3) Refining of the metal
Read the case carefully and answer the questions that follow.
Generated by claude-sonnet-4-6 · 2026-06-15 06:48 · grounding stimulus
Model Answer
(a) An ore of Mercury is Cinnabar (HgS). Mercury is present in it in the form of mercuric sulphide (HgS).
(b) When zinc carbonate is heated strongly (calcination), it decomposes to form zinc oxide and carbon dioxide:
$$\text{ZnCO}_3 \xrightarrow{\Delta} \text{ZnO} + \text{CO}_2$$
(c)
(I) Metal A is Aluminium (Al). The reaction is called Thermite reaction.
(II)
$$\text{Fe}_2\text{O}_3 + 2\text{Al} \rightarrow \text{Al}_2\text{O}_3 + 2\text{Fe} + \text{Heat}$$
This reaction is highly exothermic, producing molten iron which is used to join/weld railway tracks.
Source: Metals and Non-metals, Extraction of Metals
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Explanation
- (a) Cinnabar is the standard expected ore of mercury; students must name both ore and form of metal present.
- (b) This is calcination — heating a carbonate in limited/no air to get an oxide. Write the equation for full marks.
- (c) Thermite reaction is a classic CBSE board question. Examiners look for: correct identification of Al, the name "Thermite reaction," and a balanced equation. Don't forget to balance — 2Al and 2Fe on each side.