In the extraction of silver by Mac-Arther cyanide process, a small amount of KNO3 is also added as a — d and f Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: During the cupellation or refining step in the extraction of silver, impurities like lead, zinc, and copper must be separated from the silver. Step 2: Potassium nitrate (KNO3) is a powerful oxidizing agent used as a flux in this step. Step 3: It oxidizes the base metal impurities (such as lead and zinc) into their respective oxides, which then form a slag or are absorbed, leaving pure silver. Thus, option (b) is correct.