Electrolysis extracts highly reactive metals from ores

Steps:

• Identify reactivity series: Electrolysis suits metals above carbon (e.g., group 1 and 2).
• Examine calcium: Highly reactive group 2 metal, ore (calcium chloride) requires electrolysis to reduce molten compound.
• Compare others: Copper, lead below carbon; silver low reactivity—use chemical reduction instead.
• Confirm: Only calcium fits electrolysis for primary extraction.

Why A is correct:

• Calcium, being more reactive than carbon, cannot be reduced by it; electrolysis of molten CaCl₂ yields pure Ca at cathode per Faraday's laws.

Why the others are wrong:

• B. Copper: Extracted by roasting ore then carbon reduction in smelting, followed by electrolytic refining.
• C. Lead: Reduced from PbO ore using carbon in a blast furnace.
• D. Silver: Often found native or extracted via cyanide leaching and precipitation, not electrolysis from ore.

Final answer: A