Ответ:

Mr[H2CO3] = Ar[H] * 2 + Ar[C] + Ar[O] * 3 = 1.00794 * 2 + 12.0107 + 15.9994 * 3 = 62.02478 = 62

Mr[CuO] = Ar[Cu] + Ar[O] = 63.546 + 15.9994 = 79.5454 = 80

Mr[Na2CO3] = Ar[Na] * 2 + Ar[C] + Ar[O] * 3 = 22.98976928 * 2 + 12.0107 + 15.9994 * 3 = 105.98843856 = 106

Mr[CH4] = Ar[C] + Ar[H] * 4 = 12.0107 + 1.00794 * 4 = 16.04246 = 16

Mr[CH3COOH] = Ar[C] * 2 + Ar[H] * 4 + Ar[O] * 2 = 12.0107 * 2 + 1.00794 * 4 + 15.9994 * 2 = 60.05196 = 60

Mr[Fe2(SO4)3] = Ar[Fe] * 2 + Ar[S] * 3 + Ar[O] * 12 = 55.845 * 2 + 32.065 * 3 + 15.9994 * 12 = 399.8778 = 400

Объяснение: