JEE MAIN - Chemistry (2019 - 10th April Evening Slot - No. 16)
The INCORRECT statement is :
the color of [CoCl(NH3)5]2+ is violet as it absorbs the yellow light.
the gemstone, ruby, has Cr3+ ions occupying the octahedral sites of beryl.
the spin-only magnetic moment of [Ni(NH3)4(H2O)2]2+ is 2.83 BM.
the spin-only magnetic moments of [Fe(H2O)6]2+ and [Cr(H2O)6]2+ are nearly similar.
Explanation
(A) Complementarty color of yellow is violet. As [CoCl(NH3)5]2+ absorbs yellow so it will show complementary color violet.
(B)The building block of ruby is aluminium oxide (Al2O3) containing about 0.5 – 1% Cr3+ ions which are randomly distributed in the position normally occupied by Al3+ ions.
(C) Total number of unpaired electons in [Fe(H2O)6]2+ = 4
and total number of unpaired electons in [Cr(H2O)6]2+ = 4
So, the spin-only magnetic moments are same in both cases.
(D) Total number of unpaired electons in [Ni(NH3)4(H2O)2]2+ = 2
So, $$\mu $$ = $$\sqrt {2\left( {2 + 2} \right)} $$ BM = 2.83 BM
(B)The building block of ruby is aluminium oxide (Al2O3) containing about 0.5 – 1% Cr3+ ions which are randomly distributed in the position normally occupied by Al3+ ions.
(C) Total number of unpaired electons in [Fe(H2O)6]2+ = 4
and total number of unpaired electons in [Cr(H2O)6]2+ = 4
So, the spin-only magnetic moments are same in both cases.
(D) Total number of unpaired electons in [Ni(NH3)4(H2O)2]2+ = 2
So, $$\mu $$ = $$\sqrt {2\left( {2 + 2} \right)} $$ BM = 2.83 BM
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