Помогите химия 7 класс автор Попель номер 108,109

A) Mr (cl2) = 2 (Cl) = 2*35,5=71

Mr (O3) = 3Ar (o) = 3*16=48

Mr (P4) = 4Ar (P) = 4*31=124

b) Mr (Co) = Ar (c) + Ar (o) = 12+16=28

Mr (H2S) = 2Ar (H) + Ar (s) = 2*1+32=34

Mr (H3PO4) = 3Ar (H) + Ar (p) + 4Ar (O) = 3*1+38+4*16=98