Electrolysis extracts reactive metals from molten chlorides

Steps:

• Identify that electrolysis of molten metal chloride (e.g., MCl → M + Cl₂) produces the metal at the cathode.
• Note this method suits metals too reactive to reduce with carbon, per the reactivity series.
• Compare metals: Calcium is highly reactive (above Mg), while copper, iron, and silver are below.
• Conclude calcium requires electrolysis for extraction.

Why A is correct:

• Calcium, being highly reactive, is extracted by electrolyzing molten CaCl₂, as it cannot be reduced by carbon (reactivity series places it above carbon).

Why the others are wrong:

• B. Copper is extracted by roasting sulfide ores and self-reduction, not molten chloride electrolysis.
• C. Iron is reduced from oxide ores using carbon in a blast furnace.
• D. Silver is obtained by cyanide leaching and precipitation, not electrolysis of molten AgCl.

Final answer: A