Ответ:

Используем: K = 39, Ca = 40, Fe = 56, Cu = 64, Zn = 65, S = 32, O = 16, H = 1, N = 14, P = 31, Na = 23.

Задание 1. Ar(K) = 39; Ar(Ca) = 40; Ar(Fe) = 56; Ar(Cu) = 64; Ar(Zn) = 65.

Задание 2.

Mr(K₂SO₄) = 2 · 39 + 32 + 4 · 16 = 174.

Mr(HNO₃) = 1 + 14 + 3 · 16 = 63.

Mr(H₃PO₄) = 3 · 1 + 31 + 4 · 16 = 98.

Mr(NaOH) = 23 + 16 + 1 = 40.

Mr(Ca(OH)₂) = 40 + 2 · (16 + 1) = 74.