Freon-12 is used as a refrigerant in central home air conditioners. The rate of effusion of Freon-12 to Freon-11 (molar mass = 137.4 g/mol) is 1.07:1. The formula of Freon-12 is one of the following:
a. CF4,
b. CF3Cl,
c. CF2Cl2,
d. CFCl3, or CCl4.
Which formula is correct for Freon-12?