Chemistry NCERT Exemplar Solutions Class 12th Chapter Nine: Overview, Questions, Preparation

Using crystal field theory, draw energy level diagram, write electronic configuration of the central metal atom/ion and determine the magnetic moment value in the following: 

(i) [CoF₆]^3- ,[Co(H₂O)₆]²⁺ ,[Co(CN)₆]^3-

^{(ii) [FeF₆]3- ,[Fe(H₂O)₆]2 + ,[Fe(CN)₆]4 -}

Using valence bond theory, explain the following in relation to the complexes given below: 

[Mn(CN)₆]^3- ,[Co(NH₃)₆]³⁺ ,[Cr(H₂O)₆]³⁺ ,[FeCl]^4- 

(i) Type of hybridisation. 

(ii) Inner or outer orbital complex. 

(iii) Magnetic behaviour. 

(iv) Spin only magnetic moment value

CoSO₄Cl.5NH₃ exists in two isomeric forms ‘A’ and ‘B’. Isomer ‘A’ reacts with AgNO₃ to give white precipitate but does not react with BaCl₂ . Isomer ‘B’ gives white precipitate with BaCl₂ but does not react with AgNO₃. 

Answer the following questions. 

(i) Identify ‘A’ and ‘B’ and write their structural formulas.

(ii) Name the type of isomerism involved.

(iii) Give the IUPAC name of ‘A’ and ‘B’.  

What is the relationship between observed colour of the complex and the wavelength of light absorbed by the complex?

Why are different colours observed in octahedral and tetrahedral complexes for the same metal and same ligands?

Arrange the following complexes in the increasing order of conductivity of their solution: [Co(NH₃)₃Cl₃], [Co(NH₃)₄Cl₂]Cl, [Co(NH₃)_6]Cl₃, [Cr(NH₃)5Cl]Cl₂

A coordination compound CrCl₃.4H₂O precipitates silver chloride when treated with silver nitrate. The molar conductance of its solution corresponds to a total of two ions. Write structural formula of the compound and name it.

A complex of the type [M(AA)₂X₂]n +  is known to be optically active. What does this indicate about the structure of the complex? Give one example of such a complex.

Based on crystal field theory explain why Co(III) forms a paramagnetic octahedral complex with weak field ligands whereas it forms a diamagnetic octahedral complex with strong field ligands.

Give the electronic configuration of the following complexes based on Crystal Field Splitting theory [CoF₆]^3-,[Fe(CN)₆]^4-and [Cu(NH₃)₆]²⁺ 

Explain why [Fe(H₂O)₆]³⁺ has magnetic moment value of 5.92 BM whereas [Fe(CN)₆]^3- has a value of only 1.74 BM. 

Arrange following complex ions in increasing order of crystal field splitting energy (Δ₀)

[Cr(Cl)₆]^3- ,[Cr(CN)₆]^3- ,[Cr(NH₃)₆]³⁺ 

Name the type of isomerism when ambidentate ligands are attached to central metal ion. Give two examples of ambidentate ligands.

Which of the following complexes formed by Cu²⁺ ions are most stable?

(i) Cu²⁺ + 4NH₃⇌[Cu(NH₃)₄]²⁺,log⁡K=11.6

(ii) Cu²⁺ + 4CN−⇌[Cu(CN)₄]²⁻,log⁡K=27.3

(iii) Cu²⁺ + 2en⇌[Cu(en)₂]²⁺,log⁡K=15.4

(iv) Cu²⁺ + 4H₂O⇌[Cu(H₂O)4]²⁺,log⁡K=8.9

The colour of the coordination compounds depends on the crystal field splitting. What will be the correct order of absorption of wavelength of light in the visible region, for the complexes,  [Co(NH₃)₆]³⁺,  [Co(H₂O)₆]³⁺.

A: [Co(H₂O)₆]³⁺ > [Co(NH₃)₆]³⁺ > [Co(H₂O)₆]³⁺ .

B: [Co(NH₃)₆]³⁺ > [Co(H₂O)₆]³⁺ > [Co(CN)₆]^3- 

C: [Co(H₂O)₆]³⁺ >  [Co(NH₃)₆]³⁺ > [Co(CN)₆]^3- 

D: [Co(CN)₆]^3- >  [Co(NH₃)₆]³⁺ >  [Co(H₂O)₆]³⁺

When 0.1 mol CoCl₃(NH₃)₅ is treated with excess of AgNO₃, 0.2 mol of AgCl are obtained. The conductivity of solution will correspond to

A: 1:3 electrolyte

B: 1:2 electrolyte

C: 1:1 electrolyte

D: 3:1 electrolyte

When 1 mol [CrCl₃(H₂O)₃]₆H₂O is treated with excess of AgNO₃, 3 mol of AgCl are obtained. The formula of the complex is: 

A: [CrCl₃(H₂O)₃ ].3H₂O

B: [CrCl₂(H₂O)₄]Cl.2H₂O

C: [CrCl₂(H₂O)5]Cl₂H2O

D: [Cr(H₂O)₆]Cl₃

The correct IUPAC name of [Pt(NH₃)2Cl₂] is

(i) Diamminedichloridoplatinum (II)

(ii) Diamminedichloridoplatinum (IV)

(iii) Diamminedichloridoplatinum (0)

(iv) Dichloridodiammineplatinum (IV)

A: [Fe(CO)₅]

B: [Fe(CN)₆]^3- 

C: [Fe(C₂O₄)₃]^3- 

D: [Fe(H₂O)₆]³⁺ 

Indicate the complex ion which shows geometrical isomerism.

A: [Cr(H₂O)₄Cl₂]⁺ 

B: [Pt(NH₃)₃Cl]

C: [Co(NH₃)₆]³⁺ 

D: [Co(CN)₅](NC)^3- 

The CFSE for octahedral [CoCl₆]^4- is 18,000 cm⁻¹. The CFSE for tetrahedral [CoCl₄]^2- will be

A: 18,000 cm⁻¹

B: 16,000 cm⁻¹

C: 8,000 cm⁻¹

D: 20,000 cm⁻¹

Due to the presence of ambidentate ligands coordination compounds show isomerism. Palladium complexes of the type [Pd(C₆H₅)₂(SCN)₂] and [Pd(C₆H₅)₂(NCS)₂] are

(A) Linkage isomers

(B) Coordination isomers

(C) Ionization isomers

(D) Geometrical isomers

The compounds [Co(SO₄)(NH₃)₅] Brand [Co(SO₄)(NH₃)₅]Cl represent

A: Linkage isomerism 

B: Ionisation isomerism 

C: Coordination isomerism

D: No isomerism

A chelating agent has two or more than two donor atoms to bind to a single metal ion. Which of the following is not a chelating agent?

A: Thiosulphato 

B: Oxalato 

C Glycinato

D: Ethane-1,2-diamine

Which of the following species is not expected to be a ligand?

A: NO

B: NH₄⁺ 

C: NH₂CH₂CH₂NH₂

D: CO

What kind of isomerism exists between [Cr(H₂O)₆]Cl₃ (violet) and [Cr(H₂O)₅Cl]Cl₂⋅H₂O (greyish-green)?

A: Linkage isomerism

B: Solvate isomerism

C: Ionisation isomerism 

D: Coordination isomerism

IUPAC name of [Pt(NH₃)₂Cl(NO₂)] is 

A: Platinum diaminechloronitrite

B: Chloronitrito-N-ammineplatinum (II)

C Diamminechloridonitrito-N-platinum (II) 

D Diamminechloronitrito-N-platinate (II)

Atomic numbers of Mn, Fe, and Co are 25, 26 and 27 respectively. Which of the following inner orbital octahedral complex ions are diamagnetic?

A: [Co(NH₃)₆]³⁺ 

B: [Mn(CN)₆]^3- 

C: [Fe(CN)₆]^4- 

D: [Fe(CN)₆]^3- 

Atomic number of Mn, Fe, Co and Ni are 25, 26 27 and 28 respectively. Which of the following outer orbital octahedral complexes have same number of unpaired electrons?

A: [MnCl₆]^3- 

B: [FeF₆]^3- 

C: [CoF₆]^3- 

D: [Ni(NH₃)₆]²⁺

Which of the following options are correct for [Fe(CN)₆]^{3 -}  complex?

A: d²sp³ hybridisation 

B: sp³d² hybridisation

C: Paramagnetic 

D: Diamagnetic

An aqueous pink solution of cobalt (II) chloride changes to deep blue on addition of excess of HCl. This is because____________.

A: [Co(H₂O)]²⁺ is transformed into [CoCl₆]^4- 

B: [Co(H₂O)₆]²⁺ is transformed into [CoCl₄]^2- 

C: Tetrahedral complexes have smaller crystal field splitting than octahedral complexes. 

D: Tetrahedral complexes have larger crystal field splitting than octahedral complex.

Which of the following complexes are homoleptic?

A: [Co(NH₃)₆]³⁺ 

B: [Co(NH₃)₄]⁺ 

C: 4[Ni(CN)₄]^2- 

D: [Ni(NH₃)₄Cl₂]

Which of the following complexes are heteroleptic?

A: [Cr(NH₃)₆]³⁺ 

B: [Fe(NH₃)4Cl]⁺ 

C: [Mn(CN)₆]^4- 

D: [Co(NH₃)₆Cl₂]

Identify the optically active compounds from the following.

A: [Co(en)₃]³⁺  

B: trans - [Co(en)₂]⁺  

C: cis - [Co(en)₂Cl₂]⁺ 

D: [Cr(NH₃)₅Cl] 

Identify the correct statements for the behaviour of ethane-1, 2-diamine as a ligand.

A: It is a neutral ligand. 

B: It is a didentate ligand.

C: It is a chelating ligand. 

D: It is a unidentate ligand

Which of the following complexes show linkage isomerism?

A: [Co(NH₃)₅(NO₂)]²⁺ 

B: [Co(H₂O)₅]³⁺ 

C: [Cr(NH₃)₅SCN]²⁺ 

D: [Fe(en)₅Cl₂]⁺

Match the complex ions given in Column I with the colours given in Column II and assign the correct code

Code

(i) A (1)           B (2)          C (4)           D (5)

(ii) A (4)          B (3)          C (2)           D (1)

(iii) A (3)         B (2)          C (4)           D (1)

(iv) A (4)         B (1)          C (2)           D (3)

Match the coordination compounds given in Column I with the central metal atoms given in Column II and assign the correct code

Code

(i)   A (5)     B (4)     C (1)     D (2)

(ii)  A (3)     B (4)     C (5)     D (1)

(iii) A (4)     B (3)     C (2)     D (1)

(iv) A (3)     B (4)     C (1)     D (2)

Match the complex ions given in Column I with the hybridisation and number of unpaired electrons given in Column II and assign the correct code

Code

 (i) A (3)     B (1)      C (5)      D (2)

(ii) A (4)     B (3)      C (2)      D (1)

(iii) A (3)    B (2)      C (4)      D (1) 

(iv) A (4)     B (1)     C (2)     D (3)

Match the complex species given in Column I with the possible isomerism given in Column II and assign the correct code

Code :

(i)  A (1)     B (2)     C (4)     D (5) 

(ii) A (4)      B (3)     C (2)     D (1) 

(iii) A (4)     B (1)     C (5)     D (3) 

(iv) A (4)     B (1)     C (2)     D (3)

Match the compounds given in Column I with the oxidation state of cobalt present in it (given in Column II) and assign the correct code.

Code 

(i) A (1)     B (2)      C (4)      D (5)

(ii) A (4)    B (3)      C (2)      D (1) 

(iii) A (5)   B (1)      C (4)      D (2) 

(iv) A (4)   B (1)      C (2)      D (3)

In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

A: Assertion and reason both are true, reason is correct  of assertion. 

B: Assertion and reason both are true, but reason is not the correct  of assertion.

C: Assertion is true, reason is false.

D: Assertion is false, reason is true

1. Assertion: Toxic metal ions are removed by the chelating ligands. 

    Reason: Chelate complexes tend to be more stable.

Assertion : [Cr(H2O)6]Cl2 and [Fe(H2O)6]Cl2 are reducing in nature. 

 Reason: Unpaired electrons are present in their d-orbitals.

Assertion: Linkage isomerism arises in coordination compounds containing ambidentate ligand.                      

Reason: Ambidentate ligand has two different donor atoms.

Assertion: Complexes of MX₆ and MX₅L type (X and L are unidentate) do not show geometrical   isomerism.

Reason: Geometrical isomerism is not shown by complexes of coordination number 6.

Assertion: [Fe(CN)₆]^3- ion shows magnetic moment corresponding to two unpaired electrons.       

Reason: Because it has d²sp³ type hybridisation.

Which of the following pair of molecules contain odd electron molecule and an expanded octet molecule?

  $N_{2\left(g\right)}+3H_{2\left(g\right)}?2N{H}_{3\left(g\right)}$

20g     5g

Consider the above reaction, the limiting reagent of the reaction and number of moles of NH₃ formed respectively are:

100 mL of 5% (w/v) solution of NaCl in water was prepared in 250 mL beaker. Albumin from the egg was poured into NaCl solution and stirred well. This resulted in a/an:

The first ionization enthalpy on Na, Mg and Si, respectively, are : 496, 737 and 786 kJ mol^-1. The first ionization enthalpy (kJ mol^-1) of Al is:

In neutral of faintly alkaline medium KMnO₄ being a powerful oxidant can oxidize, thiosulphate almost quantitatively, to sulphate. In this reaction overall change in oxidation state of manganese will be:

Resistance of a conductivity cell (cell constant 129 m1) filled with 74.5 ppm solution of KCl is $100\Omega$ (labeled as solution 1). When the same cell is filled with KCl solution of 149 ppm, the resistance is $50\Omega$ (labeled as solution 2). The ratio of molar conductivity of solution 1 and solution 2 is i.e. $\frac{{\wedge }_1}{{\wedge }_2}=x\times 10^{-3}.$ The value of x is________. (Nearest integer)

Ionic radii of cation A+ and anion B are 102 and 181 pm respectively. These ions are allowed to crystallize into an ionic solid. This crystal has cubic close packing for B. A+ is present in all octahedral voids. The edge length of the unit cell of the crystal AB is________ pm.

(Nearest integer)

The minimum uncertainty in the speed of an electron in an one dimensional region of length 2a₀ (Where a₀ = Bohr radius 52.9 pm) is__________ km s^-1.

(Given: Mass of electron = 9.1 × 10^-31 kg, Planck’s constant h = 6.63 × 10^-34 Js)

When 600 mL of 0.2 M HNO₃ is mixed with 400 mL of 0.1 M NaOH solution in a flask, the rise in temperature of the flask is_________ × 10^-2 °C.

(Enthalpy of neutralization = 57 kJ mol^-1 and Specific heat of water = 4.2 JK^-1 g^-1)

(Neglect heat capacity of flask)

If O₂ gas is bubbled  through water at 303 K, the number of millimoles of O₂ gas that dissolve in 1 litre of water is______________. (Nearest integer)

(Given: Henry’s Law constant for O₂ at 303 K is 46.82 k bar and partial pressure of O₂ = 0.920 bar)

(Assume solubility of O₂ in water in too small, nearly negligible)

If the solubility product of PbS is 8 × 10^-28, then the solubility of PbS in pure water at 298 K is $x\times 10^{-16}mol{L}^{-1}.$  The value of x is__________. (Nearest integer)

[Given: $\sqrt[]{2}=1.41]$  

The reaction between X and Y is first order respect to X and zero order with respect to Y.

Examine the data of table and calculate ratio of numerical values of M and L (Nearest integer)

In a linear tetrapeptide (Constituted with different amino acids), (number of amino acids) (number of peptide bonds) is_______________.

In bromination of Propyne, with Bromine 1, 1, 2, 2-tetrabromopropane is obtained in 27% yield. The amount of 1, 1, 2, 2- tetrabromopropane obtained from 1g of Bromine in this reaction is_______________× 10^-1g. (Nearest integer) (Molar mass: Bromine = 80g / mol)

 ${\left[Fe{\left(CN\right)}_6\right]}^{3-}$ should be an inner orbital complex. Ignoring the pairing energy, the value of crystal field stabilization energy for this complex is (-) _________ ${\Delta }_0.$ (Nearest integer)