___ is a process employed to recover precious metals.

• A. Ion Exchange
• B. Electrorefining
• C. Distillation
• D. Filtration

Answer: (A)

Ion exchange captures dissolved precious metal ions by swapping them with ions on a solid resin, which allows selective removal and concentration of metals from aqueous solutions. This method is especially useful when precious metals are present at trace levels or within complex solutions, because the resin can selectively bind the target ions and then release them in a concentrated form during elution. After loading, you can recover the metals from the eluate in a much purer, more manageable form. Distillation isn’t suitable because metals in solution aren’t volatile. Filtration only removes solids, not dissolved ions. Electrorefining is a purification step that uses electrochemical deposition to refine a metal, rather than a general method to recover metals from solution.