а) первих 10 формул
б) первих 4 фотка

a)

Mr[O3] = Ar[O] * 3 = 16 * 3 = 48

Mr[FeO] = Ar[Fe] + Ar[O] = 56 + 16 = 72

Mr[CO] = Ar[C] + Ar[O] = 12 + 16 = 28

Mr[CuS] = Ar[Cu] + Ar[S] = 64 + 32 = 96

Mr[FeS2] = Ar[Fe] + Ar[S] * 2 = 56 + 32 * 2 = 120

Mr[NaOH] = Ar[H] + Ar[Na] + Ar[O] = 1 + 23 + 16 = 40

Mr[ZnCl2] = Ar[Cl] * 2 + Ar[Zn] = 35 * 2 + 65 = 136

Mr[NaBr] = Ar[Br] + Ar[Na] = 80 + 23 = 103

Mr[AlP] = Ar[Al] + Ar[P] = 27 + 31 = 58

Mr[BaCl2] = Ar[Ba] + Ar[Cl] * 2 = 137 + 35 * 2 = 208

b)

Mr[Al2O3] = Ar[Al] * 2 + Ar[O] * 3 = 27 * 2 + 16 * 3 = 102

Mr[CrSO4] = Ar[Cr] + Ar[O] * 4 + Ar[S] = 52 + 16 * 4 + 32 = 148

Mr[BaCO3] = Ar[C] + Ar[Ba] + Ar[O] * 3 = 12 + 137 + 16 * 3 = 197

Mr[AlPO4] = Ar[Al] + Ar[O] * 4 + Ar[P] = 27 + 16 * 4 + 31 = 122

Объяснение: