Coordination Compounds

NEET Chemistry · 85 questions · Page 6 of 9 · Click an option or "Show Solution" to reveal answer

Q51

Of the following complex ions, which is diamagnetic in nature?

A [NiCl 4 ] 2

-

B [Ni(CN) 4 ] 2

-

C [CuCl 4 ] 2

-

D [CoF 6 ] 3

-

Correct Answer

Option B

Solution

For [Ni(CN) 4 ] 2– Ni +2 = 3d 8 4s 0 CN– is a strong field ligand thus, it pair up the electrons.

$\therefore$ [Ni(CN) 4 ] –2 is diamagnetic in nature.

Q52

Which one of the following complexes is not expected to exhibit isomerism?

A [Ni(NH 3 ) 4 (H 2 O) 2 ] 2+

B [Pt(NH 3 ) 2 Cl 2 ]

C [Ni(NH 3 ) 2 Cl 2 ]

D [Ni(en) 3 ] 2+

Correct Answer

Option C

Solution

In [Ni(NH 3 ) 2 Cl 2 ] is in sp 3 hybridisation, thus tetrahedral in shape.

Hence the four ligands are not different to exhibit optical isomerism.

Q53

Crystal field stabilization energy for high spin d 4 octahedral complex is

-

1.8

\Delta

-

1.6

\Delta

0 + P

-

1.2

\Delta

-

0.6

\Delta

Correct Answer

Option D

Solution

$\therefore$ CFSE = [(– 3 $\times$ 0.4) + (1 $\times$ 0.6)]

\Delta

0 = – 0.6

\Delta

Q54

Which of the following complex ions is not expected to absorb visible light?

A [Ni(CN) 4 ] 2

-

B [Cr(NH 3 ) 6 ] 3+

C [Fe(H 2 O) 6 ] 2+

D [Ni(H 2 O) 6 ] 2+

Correct Answer

Option A

Solution

A transition metal complex absorbs visible light only if it has unpaired electrons.

Pairing occur because CN – is a strong field ligand.

Thus, [Ni(CN) 4 ] 2– does not contain any unpaired electron so it does not absorb visible light.

All other in the option contains pair of electrons thus absorb visible light.

Q55

Which of the following does not show optical isomerism? (en = ethylenediamine)

A [Co(NH 3 ) 3 Cl 3 ] 0

B [Co(en)Cl 2 (NH 3 ) 2 ] +

C [Co(en) 3 ] 3+

D [Co(en) 2 Cl 2 ] +

Correct Answer

Option A

Solution

The octahedral coordination compounds of the type MA 3 B 3 exhibit fac-mer isomerism.

Q56

Out of TiF 6 2

-

, CoF 6 3

-

, Cu 2 Cl 2 and NiCl 4 2

-

(Z of Ti = 22, Co = 27, Cu = 29, Ni = 28) the colourless species are

A Cu 2 Cl 2 and NiCl 4 2

-

B TiF 6 2

-

and Cu 2 Cl 2

C CoF 6 3

-

and NiCl 4 2

-

D TiF 6 2

-

and CoF 6 3

-

Correct Answer

Option B

Solution

In TiF 6 2– , Ti is present as Ti +4 Ti +4 = [Ar] 3d 0 4s 0 Hence, TiF 6 2– is colourless due to empty d orbital.

In Cu 2 Cl 2 , Cu is present as Cu + Cu + = [Ar] 3d 10 4s 0 Due to absence of unpaired electrons, Cu 2 Cl 2 is colourless.

Q57

Which of the following complex ions is expected to absorb visible light? (At. nos. Zn = 30, Sc = 21, Ti = 22, Cr = 24)

A [Ti(en) 2 (NH 3 ) 2 ] 4+

B [Cr(NH 3 ) 6 ] 3+

C [Zn(NH 3 ) 6 ] 2+

D [Sc(H 2 O) 3 (NH 3 ) 3 ] 3+

Correct Answer

Option B

Solution

In [Cr(NH 3 ) 6 ] 3+ , Cr is present as Cr +3 Cr +3 = [Ar] 3d 3 4s 0 Due to presence of 3 unpaired electrons it absorbs light of visible region.

Q58

In which of the following coordination entities the magnitude of

\Delta

o (CFSE in octahedral field) will be maximum? (At. No. Co = 27)

A [Co(CN) 6 ] 3

-

B [Co(C 2 O 4 ) 3 ]3

-

C [Co(H 2 O) 6 ] 3+

D [Co(NH 3 ) 6 ] 3+

Correct Answer

Option A

Solution

In all the given options the central metal atom is same and contain same number of d electrons.

Thus, CFSE is decided by ligands.

In case of strong field ligand, CFSE is maximum, CN – is a strong field ligand hence is [Co(CN) 6 ] 3– so CFSE is maximum.

Q59

Which of the following complexes exhibits the highest paramagnetic behaviour? where gly = glycine, en = ethylenediamine and bpy = bipyridyl moities. (At. nos. Ti = 22, V = 23, Fe = 26, Co = 27)

A [Co( ox ) 2 (OH) 2 ]

-

B [Ti(NH 3 ) 6 ] 3+

C [V( gly ) 2 (OH) 2 (NH 3 ) 2 ] +

D [Fe( en )( bpy )(NH 3 ) 2 ] 2+

Correct Answer

Option A

Solution

In [Co( ox ) 2 (OH) 2 ] $-$ Co +5 = [Ar] 3d 4 (4 unpaired electrons) OX and OH are weak field ligands.

In [Ti(NH 3 ) 6 ] 3+ Ti +3 = [Ar] 3d 1 (one unpaired electron) In [V(gly) 2 (OH) 2 (NH 3 ) 2 ] + V +5 = [Ar] 4r 0 3d 0 (no unpaired electron) In [Fe( en )( bpy )(NH 3 ) 2 ] 2+ Fe +2 = [Ar] 3d 6 (4 unpaired electrons) But due to presence of strong field ligand like NH 3 , bpy and en thus Fe +2 contains no unpaired electron.

$\therefore$ Complex [Co( ox ) 2 (OH) 2 ] $-$ has maximum number of unpaired electrons, thus show maximum paramagnetism.

Q60

The d electron configurations of Cr 2+ , Mn 2+ , Fe 2+ and Ni 2+ are 3d 4 , 3d 5 , 3d 6 and 3d 8 respectively. Which one of the following aqua complexes will exhibit the minimum paramagnetic behaviour? (At. No. Cr = 24, Mn = 25, Fe = 26, Ni = 28)

A [Fe(H 2 O) 6 ] 2+

B [Ni(H 2 O) 6 ] 2+

C [Cr(H 2 O) 6 ] 2+

D [Mn(H 2 O) 6 ] 2+

Correct Answer

Option B

Solution

Cr 2+ = 3d 4 (4 unpaired electrons) Mn 2+ = 3d 5 (5 unpaired electrons) Fe 2+ = 3d 6 (4 unpaired electrons) Ni 2+ = 3d 8 (2 unpaired electrons) Thus, [Ni(H 2 O) 6 ] 2+ exhibit minimum paramagnetic behaviour.

Greater the number of unpaired electrons, higher is the paramagnetism.

Hence Ni 2+ will exhibit the minimum paramagnetic behaviour.

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