Question: 1 ) Among the following complexes (K-P) K₃[Fe(CN)₆] (K), [Co(NH₃)₆]Cl₃ (L),  Na₃[Co(Oxalate)₃] (M), [Ni(H₂O)₆]Cl₂ (N), K₂[Pt(CN)₆] (O) and [Zn(H₂O)₆](NO₃)₂ (P). The diamagnetic complexes are  (IIT JEE -2012)

1) K, L, M, N

2) K, M, O, P

3) L, M, O ,P

4) L, M ,N ,O

Answer: C

Solution:

Complex	MetalIon	system	Complex Spin	Electronic Configuration	No. of Unpaired electrons	Magnetic Property
K3[Fe(CN)6]	Fe(III)	d5	Low Spin	t2g5 eg0	1	Paramagnetic
[Co(NH3)6]Cl3	Co(III)	d6	Low Spin	t2g6 eg0	0	Diamagnetic
Na3[Co(Oxalate)3]	Co(III)	d6	Low Spin	t2g6 eg0	0	Diamagnetic
[Ni(H2O)6]Cl2	Ni(II)	d8	High Spin	t2g6 eg2	2	Paramagnetic
K2[Pt(CN)6]	Pt(IV)	d6	Low Spin	t2g6 eg0	0	Diamagnetic
[Zn(H2O)6](NO3)2	Zn(II)	d10	Low Spin	t2g6 eg4	0	Diamagnetic

Hence, the correct option is C.

Question: 2 ) As per IUPAC nomenclature, the name of the complex [Co(H₂O)₄(NH₃)₂]Cl₃ is     

1) Tetraaquadiaminecobalt (III) chloride.

2) Tetraaquadiamminecobalt (III) chloride.

3) Diaminetetraaquacobalt (III) chloride.

4) Diamminetetraaquacobalt (III) chloride.  (IIT JEE -2012)

Answer: D

Solution:

The compound contains 4 H₂O ligand and 2 NH₃ ligand. Both of these are neutral so there names

would be used as such without adding any prefix of suffix. i.e. aqua and ammine.

Acording to alphabetical order ammine would come before aqua.

So, the IUPAC name is  Diamminetetraaquacobalt (III) chloride.

Hence, the correct option is d.

Question 3) Geometrical shapes of the complexes formed by the reaction of Ni²⁺ with Cl^-, CN^- and H₂O, respectively are  (IIT JEE  2011)

1) octahedral, tetrahedral and square planar.

2) tetrahedral, square planar and octahedral.

3) square planar, tetrahedral and octahedral.

4) octahedral, square planar and octahedral.

Answer: b

Solution

Metal Ion	Ligand	Complex	Geometry
Ni2+	Cl-	[NiCl4]2-	Tetrahedral
Ni2+	CN-	[Ni(CN)4]2-	Square Planar
Ni2+	H2O	[Ni(H2O)6]2+	Octahedral

Hence, the correct option is B.