JEE Advanced 2018 · Paper 1 · Chemistry Q7

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ChemistryNumerical+3Question 25 of 54

Among the species given below, the total number of diamagnetic species is ______.

H atom, $\ce{NO2}$ monomer, $\ce{O2-}$ (superoxide), dimeric sulphur in vapour phase, $\ce{Mn3O4}$ , $\ce{(NH4)2[FeCl4]}$ , $\ce{(NH4)2[NiCl4]}$ , $\ce{K2MnO4}$ , $\ce{K2CrO4}$

Your answer

Answer and worked solution

Official answer: 1

Count unpaired electrons:

Species	Unpaired electrons
H atom	1
$\ce{NO2}$ (odd-electron)	1
$\ce{O2-}$	1
$\ce{S2}$ (vapour, like $\ce{O2}$ )	2
$\ce{Mn3O4}$ ( $\ce{Mn^{2+}}$ , $\ce{Mn^{3+}}$ )	many
$\ce{[FeCl4]^{2-}}$ (Fe²⁺, d⁶, high spin)	4
$\ce{[NiCl4]^{2-}}$ (Ni²⁺, d⁸, tetrahedral)	2
$\ce{K2MnO4}$ (Mn(VI), d¹)	1
$\ce{K2CrO4}$ (Cr(VI), d⁰)	0

Only $\ce{K2CrO4}$ is diamagnetic.

Answer: 1

Topics:Magnetic properties and colour Molecular orbital theory Transition element properties

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JEE Advanced 2018 · Paper 1, Chemistry question 7