Coordination Compounds

NEET Chemistry · 85 questions · Page 8 of 9 · Click an option or "Show Solution" to reveal answer

Q71

The number of unpaired electrons in the complex ion [CoF 6 ] 3

-

is (Atomic no. : Co = 27)

A 2

B 3

C 4

D zero

Correct Answer

Option C

Solution

Thus, the number of unpaired electrons = 4.

Q72

Among the following which is not the

\pi

-bonded organometallic compound?

A K [PtCl 3 (

\eta

-

C 2 H 4 )]

B Fe (

\eta

-

C 5 H 5 ) 2

C Cr (

\eta

-

C 6 H 6 ) 2

D (CH 3 ) 4 Sn

Correct Answer

Option D

Solution

$\pi$ -bonded organometallic compound includes organometallic compounds of alkenes, alkynes and some other carbon containing compounds having electrons in their p orbitals.

Q73

Atomic number of Cr and Fe are respectively 24 and 26, which of the following is paramagetic with the spin of electron?

A [Cr(CO) 6 ]

B [Fe(CO) 5 ]

C [Fe(CN) 6 ] 4

-

D [Cr(NH 3 ) 6 ] 3+

Correct Answer

Option D

Solution

Atoms, ions or molecules containing unpaired electrons are paramagnetic.

In [Cr(NH 3 ) 6 ] 3+ Cr +3 = [Ar]3d 3 4s 0 NH 3 is weak field ligand so pairing of d-electrons take place odes not happen.

Here, Number of unpaired electrons = 3 So it is paramagnetic.

In other cases pairing of d-electrons take place in presence of strong field ligands such as CO or CN – .

Q74

CuSO 4 when reacts with KCN forms CuCN, which is insoluble in water. It is soluble in excess of KCN, due to formation of the following complex

A K 2 [Cu(CN) 4 ]

B K 3 [Cu(CN) 4 ]

C CuCN 2

D Cu[KCu(CN) 4 ].

Correct Answer

Option B

Solution

Copper sulphate react with KCN to give white ppt of CuCN and cyanogen gas.

The insoluble copper cyanide dissolve in excess of KCN and give soluble potassium cuprocyanide 2CuSO 4 + 4KCN $\to$ 2CuCN + (CN) 2 + 2K 2 SO 4 CuCN + 3KCN $\to$ K 3 [Cu(CN) 4 ]

Q75

The hypothetical complex chloro diaquatriammine cobalt(III) chloride can be represented as

A [CoCl(NH 3 ) 3 (H 2 O) 2 ]Cl 2

B [Co(NH 3 ) 3 (H 2 O)Cl 3 ]

C [Co(NH 2 ) 3 (H 2 O) 2 Cl]

D [Co(NH 3 ) 3 (H 2 O) 3 ]Cl 3

Correct Answer

Option A

Solution

The hypothetical complex chloro diaquatriammine cobalt(III) chloride can be broken down as follows : chloro indicates the presence of a chloride ion (Cl⁻) as a ligand. diaqua indicates the presence of two water molecules (H₂O) as ligands. triammine indicates the presence of three ammonia molecules (NH₃) as ligands. cobalt(III) indicates that cobalt is in the +3 oxidation state.

The additional chloride at the end suggests the presence of chloride ions outside the coordination sphere, likely as counterions.

Given this, let's analyze the options : Option A - [CoCl(NH₃)₃(H₂O)₂]Cl₂ : This matches the description.

It has one chloro ligand, three ammonia ligands, two water ligands, and two chloride ions as counterions, with cobalt in the +3 oxidation state.

Option B - [Co(NH₃)₃(H₂O)Cl₃] : Incorrect, as it suggests three chloride ligands inside the coordination sphere, which is not specified in the name.

Option C - [Co(NH₂)₃(H₂O)₂Cl] : Incorrect, as NH₂ is not the same as NH₃ (ammonia), and it also suggests a different ligand arrangement.

Option D - [Co(NH₃)₃(H₂O)₃]Cl₃ : Incorrect, as it has three water molecules instead of two and lacks the chloro ligand inside the coordination sphere.

Therefore, the correct representation is Option A - [CoCl(NH₃)₃(H₂O)₂]Cl₂ .

Q76

In the silver plating of copper, K[Ag(CN) 2 ] is used instead of AgNO 3 . The reason is

A a thin layer of Ag is formed on Cu

B more voltage is required

C Ag + ions are completely removed from solution

D less availability of Ag + ions, as Cu can not displace Ag from [Ag(CN) 2 ]

-

ion.

Correct Answer

Option D

Solution

Copper being more electropositive readily precipitate silver from their salt (Ag + ) solution.

Cu + 2AgNO 3 $\to$ Cu(NO 3 ) 2 + Ag In K[Ag(CN) 2 ] solution a complex anion [Ag(CN) 2 ] – is formed so Ag + ions are less available in the solution and Cu cannot displace Ag from this complex ion.

Q77

Which of the following organometallic compounds is

\sigma

and

\pi

bonded?

A [Fe(

\eta

-

C 2 H 5 ) 2 ]

B K[PtCl 3 (

\eta

-

C 2 H 4 )]

C [Co(CO) 5 NH 3 ] 2+

D Fe(CH 3 ) 3

Correct Answer

Option C

Solution

[Co(CO) 5 NH 3 ] 2+ : In this complex, Co-atom is attached with NH 3 through $\sigma$ bonding and with CO with dative $\pi$ -bond.

Q78

Coordination number of Ni in [Ni(C 2 O 4 ) 3 ] 4

-

A 3

B 6

C 4

D 2

Correct Answer

Option B

Solution

Coordination number of nickel in [Ni(C 2 O 4 ) 3 ] 4 $-$ is 6 because C 2 O 4 2– is a bidentate ligand.

Q79

Which of the following will exhibit maximum ionic conductivity?

A K 4 [Fe(CN) 6 ]

B [Co(NH 3 ) 6 ]Cl 3

C [Cu(NH 3 ) 4 ]Cl 2

D [Ni(CO) 4

Correct Answer

Option A

Solution

Ionic conductance increases with increasing the number of ions, produced after decomposition.

In K 4 [Fe(CN) 6 ], it produces maximum 5 ions thus show more conductivity.

K 4 [Fe(CN) 6 ] ⇌ 4K + + [Fe(CN) 6 ] 4–

Q80

Which of the following will give maximum number of isomers?

A [Co(NH 3 ) 4 Cl 2 ]

B [Ni(en)(NH 3 ) 4 ] 2+

C [Ni(C 2 O 4 )(en) 2 ] 2

-

D [Cr(SCN) 2 (NH 3 ) 4 ] +

Correct Answer

Option D

Solution

In [Cr(SCN) 2 (NH 3 ) 4 ] + it shows linakge, geometrical and optical isomerism.

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