Lead, tin and bismuth are purified by liquation method. — Metallurgy and Isolation of Elements Chemistry Question

💡 Solution & Explanation

Step 1: Analyze the refining methods: liquation is based on difference in melting points; distillation is based on difference in boiling points; zone refining is based on fractional crystallization. Step 2: Cupellation is a refining process used for metals (like silver or gold) that have low affinity for oxygen. Impure metals are heated under a blast of air, which oxidizes the more reactive impurities (such as lead, copper, or tin) to form dross/volatile oxides, leaving the unoxidized precious metal behind. Step 3: Therefore, cupellation is the correct purification method for metals with low oxygen affinity, matching option (d).