The magnetic moment of complex given below are in the order:
(I) `[Ni(CO)_(4)]`
(II) `[Mn(CN)_(6)]^(4-)`
(III) `[Cr(NH_(3))_(6)]^(3+)`
(IV) `[CoF_(6)]^(3-)`

Valence bond theory successfully explains the magnetic behaviour of complexes. The substances which contains unpaired electrons are paramagnetic and paramagnetic character increases as the number of unpaired electrons increases. Magnetic moment of a complex can be determined experimentally and by using formula sqrt(n(n+2)) and we can determine the number of unpaired electrons in it. This information is important in writing electronic structure of complex which in turn also useful in deciding the geometry of complex. The magnetic moment of complexes given below are in the order : {:(Ni(CO)_(4),[Mn(CN)_(6)]),("(I)","(II)"),([Cr(NH_(3))_(6)]^(3+),[CoF_(6)]^(3+)),("(I)","(II)"):}

Amongst I=[Co(Ox)_(3)]^(3-),II=[CoF_(6)]^(3-),III=[Co(NH_(3))_(6)]^(+3)

Which of the followimg complex compound(s) is/are paramagnetic and low spin? (I) K_(3)[Fe(CN_(6))] (II) [Ni(CO)_(4)]^(0) (III) [Cr(NH_(3))_(6)]^(3+) (IV) [Mn(CN)_(6)]^(4-)

Which of the followimg complex compound(s) is/are paramagnetic and low spin? (I) K_(3)[Fe(CN_(6))] (II) [Ni(CO)_(4)]^(0) (III) [Cr(NH_(3))_(6)]^(3+) (IV) [Mn(CN)_(6)]^(4-)

The magnetic moments of complexes given below are in the order: [Atomic no. Ti = 22 , Cr = 24 , Fe = 26 , Ni = 28 ] [FeF_(6)]^(3-) [Ti(H_(2)O)_(6)]^(3+) [Cr(NH_(3))_(6)]^(3+) [Ni(H_(2)O)_(6)]^(2+)

The magnetic moments of complexes given below are in the order: [Atomic no. Ti = 22 , Cr = 24 , Fe = 26 , Ni = 28 ] [FeF_(6)]^(3-) [Ti(H_(2)O)_(6)]^(3+) [Cr(NH_(3))_(6)]^(3+) [Ni(H_(2)O)_(6)]^(2+)