JIPMER2015ChemistryGeneral Principles and Processes of Isolation of Metals
The major role of fluorspar ( CaF ₂ ) which is added in small quantity in the electrolytic reduction of alumina dissolved in fused cryolite ( Na ₃ AlF ₆ ) is I. as a catalyst. II. to make the fused mixture very conducting. III. to lower the temperature of melting. IV. to decrease the rate of oxidation of carbon at the anode.
Options
- AI, II
- BII, III
- CI, II, III
- DIII, IV
Correct answer
B. II, III
Step-by-step solution
Fluorspar is added in small quantity in the electrolytic reduction of alumina dissolved in fused cryolite ( Na ₃ AlF ₆ ) to make the fused mixture more conducting and to lower the melting point of fused mixture at 1140 K .