JEE Main 2019 — D And F Block Elements Question with Solution
From: JEE Main 2019 (Online) 10th April Evening Slot
Question
The INCORRECT statement is :
Choose an option
Show full solutionCorrect option: B
Correct answer
Bthe gemstone, ruby, has Cr3+ ions occupying the octahedral sites of beryl.
Step-by-step 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, = 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, = BM = 2.83 BM
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This is a previous-year question from JEE Main 2019, covering the D And F Block Elements chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.