Given below are two statements:
Statement I : During Electrolytic refining, the pure metal is made to act as anode and its impure metallic form is used as cathode.
Statement I I: During the Hall-Heroult electrolysis process, purified Al₂ O₃ is mixed with Na₃ AlF₆ to lower the melting point of the mixture.
In the light of the above statements, choose the most appropriate answer from the options given below:

Solution

Chemistry ma’am · 3 steps

Impure metal is the anode that dissolves, and pure metal builds up on the cathode.

1. Statement I. In electrolytic refining the impure metal is the anode and a thin strip of pure metal is the cathode. The anode dissolves into the electrolyte as metal ions, and pure metal deposits on the cathode. The statement swaps the two, so it is incorrect.

   Anode: Cu → Cu²⁺ + 2e⁻ Cathode: Cu²⁺ + 2e⁻ → Cu

2. Statement II. Pure Al₂O₃ melts above 2000 °C. In the Hall-Heroult process it is mixed with cryolite, Na₃AlF₆, and often CaF₂, which lowers the melting point of the mixture a great deal and makes the melt conduct better. The statement is correct.
3. So. Statement I is incorrect and Statement II is correct, which is option (b).

The idea to keep. In electrolytic refining the impure block is always the anode, because it has to dissolve. The pure metal collects on the cathode, and impurities fall below the anode as anode mud.

Answer from the NTA final answer key. Solution by PrepWiser.