On the basis of reactivity metals are grouped into three categories –
(i) Metals of low reactivity
(ii) Metals of medium reactivity
(iii) Metals of high reactivity
Therefore metals are extracted in pure form from their ores on the basis of their chemical properties.
Metals of high reactivity are extracted from their ores by electrolysis of the molten ore.
Metals of low reactivity are extracted from their sulphide ores, which are converted into their oxides. The oxides of these metals are reduced to metals by simple heating.
Answer the sub-parts based on the given passage about extraction of metals.
Generated by claude-sonnet-4-6 · 2026-06-15 06:50 · grounding stimulus
Model Answer
(a) A metal that reacts vigorously with both air and water belongs to the high reactivity group. The process used is electrolysis of its molten ore.
(b) Aluminium is a highly reactive metal, more reactive than carbon. Therefore, carbon cannot displace aluminium from its oxide — carbon is not a strong enough reducing agent. Electrolysis is used instead.
(c) Cinnabar (HgS) is first roasted in air to convert it into mercuric oxide (HgO). On further heating, HgO decomposes to give mercury metal:
$$\text{2HgS} + 3\text{O}_2 \xrightarrow{\Delta} 2\text{HgO} + 2\text{SO}_2$$
$$2\text{HgO} \xrightarrow{\Delta} 2\text{Hg} + \text{O}_2$$
Source: Metals and Non-metals, Extraction of Metals section
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Explanation
- (a) Points directly to high-reactivity metals → electrolysis, as stated in the passage.
- (b) Standard NCERT reasoning: Al is higher than C in the reactivity series, so C cannot reduce Al₂O₃.
- (c) Examiners expect both equations clearly written. Cinnabar = HgS; the two-step process (roasting → thermal decomposition) is the key. Mercury is a low-reactivity metal, consistent with the passage.