Which has lower freezing point freon 11 or freon 12?

Refrigerants do not freeze. They are used due to their favorably low boiling points, so I am going to assume that is what you are asking. The answer would be R-12 which boils at -21.6*F where R-11 boils at 74.7*F. These listed boiling points are at atmospheric pressure at sea level (0 psig/ 14.7 psia).