Mr[CH4] = Ar[C] + Ar[H] * 4 = 12 + 1 * 4 = 16
Mr[C2H4] = Ar[C] * 2 + Ar[H] * 4 = 12 * 2 + 1 * 4 = 28
Mr[HCl] = Ar[H] + Ar[Cl] = 1 + 35 = 36
Mr[H2S] = Ar[H] * 2 + Ar[S] = 1 * 2 + 32 = 34
Объяснение:
