1) Mr(CCl2F2) = 12 + 35*2 + 19*2 = 120
W(C) = Ar(C) * n / Mr(CCl2F2) *100% = 12 *1 / 120 *100% = 10%
W(Cl) = Ar(Cl) *n / Mr(CCl2F2) *100% = 35*2 / 120 *100% =58,3%
W(F) = Ar(F) * n / Mr(CCl2F2) *100% = 19*2 / 120 *100% =31,7%
2) 2Fe + 3Cl2 -> 2FeCl3
2Al + 3S -> Al2S3
C + O2 -> CO2
FeO + H2 -> Fe + H2O