Electrolysis extracts highly reactive metals from ores

Steps:

• Recall that electrolysis uses electrical energy to reduce metal ions in molten or aqueous ores, suitable for reactive metals not reducible by carbon.
• Check reactivity series: Calcium (Group 2) is highly reactive, above carbon, so requires electrolysis.
• Compare others: Copper, lead, and silver are below carbon, allowing chemical reduction methods.
• Conclude only calcium fits electrolysis criterion for ore extraction.

Why A is correct:

• Calcium is extracted via electrolysis of molten calcium chloride (CaCl₂), where Ca²⁺ ions gain electrons at cathode: Ca²⁺ + 2e⁻ → Ca.

Why the others are wrong:

• B. Copper is extracted from oxide ore by reduction with carbon or hydrogen, not electrolysis.
• C. Lead is extracted from sulfide ore (galena) by roasting and carbon reduction.
• D. Silver is extracted from sulfide ore by roasting or cyanide leaching, followed by precipitation.

Final answer: A