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Question:

The INCORRECT statement is:
A. The spin-only magnetic moments of [Fe(H₂O)₆]²⁺ and [Cr(H₂O)₆]²⁺ are nearly similar
B. The spin-only magnetic moment of [Ni(NH₃)₄(H₂O)₂]²⁺ is 2.83 BM
C. The gemstone, ruby, has Cr³⁺ ions occupying the octahedral sites of beryl
D. The color of [CoCl(NH₃)₅]²⁺ is violet as it absorbs the yellow light

The spin - only magnetic moments of[Fe(H2O)6]2and[Cr(H2O)6]2are nearly similar

The spin-only magnetic moment of[Ni(NH3)4(H2O)2]2is2.83 BM

The gemstone, ruby, hasCr3+ions occupying the octahedral sites of beryl

The color of[CoCl(NH3)5]2is violet as it absorbs the yellow light

Solution:

Correct option is C. The gemstone, ruby, has Cr³⁺ ions occupying the octahedral sites of beryl
(1) [Fe(H₂O)₆]²⁺, Fe²⁺ → 3d⁶ unpaired electrons
[Cr(H₂O)₆]²⁺, Cr²⁺ → 3d⁴ unpaired electrons
(2) [Ni(NH₃)₄(H₂O)₂]²⁺, Ni²⁺ → 3d⁸ unpaired electrons μₘ = 2.83 B.M
(3) In gemstone, ruby has Cr³⁺ ion occupying the octahedral sites of aluminium oxide (Al₂O₃) normally occupied by Al³⁺ ion
(4) The complementary color of violet is yellow.