Highly reactive metals such as sodium, magnesium and calcium are extracted by electrolysis of their molten ch…

Question

Highly reactive metals such as sodium, magnesium and calcium are extracted by electrolysis of their molten chlorides rather than by reduction with carbon. The best reason for this is:
(A) Carbon is too expensive
(B) These metals have greater affinity for oxygen than carbon does
(C) Electrolysis is a cheaper process
(D) Their chlorides do not melt easily

Accepted Answer

## Model Answer **(B) These metals have greater affinity for oxygen than carbon does** ## Explanation The textbook (Section 3.4.5) explicitly states: "carbon cannot reduce the oxides of sodium, magnesium, calcium, aluminium, etc., because **these metals have more affinity for oxygen than carbon**." This makes carbon ineffective as a reducing agent for these metals, so electrolysis is used instead. Option B is the *reason*, not just a consequence — examiners expect this conceptual distinction.

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