Ответ:
Используем: He = 4, Ar = 40, Ba = 137, Ag = 108, I = 127, O = 16, P = 31, S = 32, H = 1, C = 12.
Задание 1. Ar(He) = 4; Ar(Ar) = 40; Ar(Ba) = 137; Ar(Ag) = 108; Ar(I) = 127.
Задание 2.
Mr(O₃) = 3 · 16 = 48.
Mr(P₄) = 4 · 31 = 124.
Mr(S₈) = 8 · 32 = 256.
Mr(H₂O₂) = 2 · 1 + 2 · 16 = 34.
Mr(CO) = 12 + 16 = 28.
