A complex of a certain metal ion has a magnetic moment of 4.90 B.M. Another complex of the same metal ion in the same oxidation state has a zero magnetic moment. Which of the following could be the central metal ion in the two complexes?


Correct option is



Since the magnetic moment of the complex is 4.90 BM so it contains 4 unpaired electrons  in its oxidation state of complex.

Since another complex of the same metal ion in the same oxidation state shows zero magnetic moment, so in this complex there is no unpaired electron. 

To have either four or zero unpaired electrons in the complexes of the metal in this oxidation state is d6.  

        Mn    3d54s; Mn2+ ; 3d5   

        Fe      3d64s; Fe3+ ; 3d

        Fe      3d64s2 ; Fe2+ ; 3d6

        Cr      3d54s1 ; Cr3+ ; 3d3  

i.e., the correct option is Fe2+.



Which of the following is a spin paired complex ion?


Which of the following complexes does not show the geometric isomerism?


The ion  is expected to have x isomers. x is



Which method can be used to distinguish

[Co(NH3)6][Cr(NO2)6] and [Cr(NH3)6][Co(NO2)6]


Select the complex that involves outer hybridization of central metal ion.


A complex containing Mn2+ and Br ion was found to have a magnetic moment of 5.92 BM. The probable formula and geometry of the complex is most likely to be :



A solution of ‘X’ containing 0.02 mole of ‘X’ per litre is mixed with another solution, a solution of ‘Y’ containing 0.02 mole of ‘Y’ per litre. 

     1 L of mixture solution + AgBO3 → ‘A’ ↓ 

     1 L of mixture solution + Excess BaCl2 → ‘B’↓  

If  ‘X’ is [Co(NH3)5SO4]Br, and    

     ‘Y’ is [Co(NH3)5Br]SO4,

then the number of moles of ‘A’ and ‘B’ obtained are, respectively


The splitting of degenerate d-orbitals in the formation of certain complex was observed as shown below


This type of splitting of d-orbitals occurs in the formation of


Which is not a π-acceptor ligand?


Which of the following is most acidic aqua ion?