JEE Advance - Chemistry (2018 - Paper 1 Offline - No. 6)
$$H$$ atom, $$N{O_2}$$ monomer, $${O_2}^ - $$ (superoxide), dimeric sulphur in vapor phase, $$M{n_3}{O_4},\,\,$$ $${\left( {N{H_4}} \right)_2}\left[ {FeC{l_4}} \right],$$ $${\left( {N{H_4}} \right)_2}\left[ {NiC{l_4}} \right],\,$$ $$\,{K_2}Mn{O_4},\,$$$${K_2}Cr{O_4}$$
Explanation
Among the given species only K2CrO4 is diamagnetic as central metal atom Cr in it has [Ar]3d0 electronic configuration i.e., all paired electrons. The structure and oxidation state of central metal atom of this compound are as follows
Structure
Oxidation state Cr6+
Rest all the compounds are paramagnetic. Reasons for their paramagnetism are given below.
(i) H-atom have 1s1 electronic configuration i.e., 1 unpaired electron.
(ii) NO2 i.e.
in itself is an odd electron species.
(iii) O$$_2^ - $$ (Superoxide) has one unpaired electron in $$\pi$$* molecular orbital.
(iv) S2 in vapour phase has O2 like electronic configuration i.e., have 2 unpaired electrons in $$\pi$$* molecular orbitals.
(v) Mn3O4 has following structure
Thus, Mn is showing +2 and +4 oxidation states. The outermost electronic configuration of elemental Mn is 3d54s2. Hence, in both the above oxidation states it has unpaired electron as
(vii) (NH4)2NiCl4 has Ni as central metal atom with +2 oxidation state. The electronic configuration of Ni2+ in the complex is
(viii) In K2MnO4 central metal atom Mn has +6 oxidation state with following structure
Electronic configuration of Mn6+ is
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