What is anode mud in the electrolytic refining of metals (or) plating process?

In the electrolytic refining of metals, anode mud refers to the insoluble substances that remain at the bottom of the anode during the electrolysis process. These substances are typically impurities that do not dissolve into the electrolyte and are collected as a residue. Therefore, the correct answer is: b) Insoluble substances

In electrolytic refining, the anode consists of impure metal, and the cathode is a thin strip of high-purity metal. The electrolyte is a solution of metal salts.

When electric current passes through the electrolyte, pure metal from the anode dissolves into the electrolyte and gets deposited at the cathode. The insoluble impurities settle down at the bottom of the anode and are known as anode mud or anode slime.