Two unknown 3d transition metal chlorides, Salt A and Salt B, are tested with aqueous potassium ferrocyanide, K ₄[ Fe ( CN )₆] . Salt A produces a chocolate brown precipitate, while Salt B produces a Prussian blue precipitate. The spin-only magnetic moments (in BM) of the metal cations present in Salt A and Salt B, respectively, are:

Step-by-step solution

The reaction of metal cations with potassium ferrocyanide, K ₄[ Fe ( CN )₆] , gives characteristic precipitates. Salt A forms a chocolate brown precipitate, which indicates the presence of the Cu ²⁺ ion. The precipitate is cupric ferrocyanide, Cu ₂[ Fe ( CN )₆] . The electronic configuration of Cu ²⁺ is [ Ar ] 3d^9 . It has 1 unpaired electron ( n = 1 ). Spin-only magnetic moment = n(n+2) = 1(1+2) = 3 1.73 BM . Salt B forms a Prussian blue precipitate, which indicates the presence of the Fe ³⁺ ion. The precipitate