UPSEE Solved Model Paper 4

The major role of fluorspar (CaF2) which isadded in small quantity in the electrolytic reductionof alumina dissolved in fused cryolite (Na3AlF6) is :
I. to act as a catalyst
II. to make the fused mixture very conduction
III. to lower the temperature of melting
IV. to decrease the rate of oxidation of carbon at the anode