1. Mr (Fe(OH)2) = Ar(Fe) + 2 × Ar(O) + 2 × Ar(H).Ar(Fe) = 56, Ar(O) = 16, Ar(H) = 1.Mr (Fe(OH)2) = 56 + 2 × 16 + 2 × 1 = 56 + 32 + 2 = 90.
Ответ: 90