CBSE Class 12 Chemistry Coordination Compounds Questions

Question: Which one of the following complexes will consume more equivalents of aqueous solution of AgNO₃?
a) Na₂ [CrCl₆]
b) [Cr(H₂O)₅ Cl]Cl₂
c) [Cr(H₂O)₆]Cl₃
d) Na₂[CrCl₅(H₂O)]

Answer: c

Question: In which compound, synergic effect is present?
a) [Ni(CO)₄] 
b) [NiCl₄]^2–
c) [CuCl₄]²⁻
d) [Mn(H₂O)₆]²⁺

Answer: a

Question: The primary and secondary valencies of chromium in the complex ion, dichlorodioxalato chromium (III) respectively are
a) 3 and 4
b) 4 and 3
c) 6 and 3
d) 3 and 6

Answer: d

Question: Gold combines with cyanide in the presence of oxygen and water to form coordination entity in aqueous solution. The coordination entity is
a) [Au(CN)₂]⁻
b) [Au(CN)₂]²⁻
c) [Au(CN)₂]³⁻
d) [Au(CN)₂]⁴⁻

Answer: a

Question: How many ions obtain after dissociation of this complex [Co(NH₃)₆]Cl₃?
a) 3
b) 2
c) 5
d) 4

Answer: d

Question: Coordination complex X gives white ppt. with AgNO₃ solution while its isomer Y gives white ppt but with BaCl₂. Two compounds are isomer of CuClSO_4.5NH₃. The possible formula of X and Y are  

                 X                                              Y
a) [Cu(NH₃)₅SO₄]Cl                       [Cu(NH₃)₅Cl]SO₄
b) [Cu(NH₃)₅Cl]SO₄                       [Cu(NH₃)₅SO₄]Cl   
c) [Cu(NH₃)₄ClSO₄]NH₃                 [Cu(NH₃)₅Cl]SO₄
d) [Cu(Br)₅NH₃]SO₄                       [Cu(Br)₄(NH₃)SO₄]Br   

Answer: a

Question: Coordination number of Pt and Ni in [PtCl₆]^2– and [Ni(NH₃)₄]²⁺ are respectively.
a) 4 and 6
b) 6 and 4
 c) 4 and 4
d) 6 and 6

Answer: b

Question: The pair of compounds having metals in their highest oxidation states is
a) [MnO₄]–,CrO₂Cl₂
b) [NiCl₄]^2–, [CoCl₄]^–
c) MnO₂ , FeCl₃
d) [Fe(CN)₆]_3– , [Co(CN)₆]₋₃

Answer: a

Question: The complex, [Pt(py)(NH₃)BrCl]  will have how many geometrical isomers?
a) 2
b) 3
c) 4
d) 0

Answer: b

Question: Which among the following will be named as dibromidobis (ethylenediammine) chromium (III) bromide ?
a) [Cr(en)₃]Br₃
b) [Cr(en)₂ Br₂]Br 
c) [Cr(en)Br₄]⁻
d) [Cr(en)Br₂]Br 

Answer: b

Question: The oxidation state of Fe in the brown ring complex [Fe(H₂O)₅NO]SO₄ is
a) +3
b) 0
c) +2
d) +1

Answer: d

Question: According to IUPAC nomenclature sodium nitroprusside is named as
a) sodium pentacyanonitrosyl ferrate (II)
b) sodium pentacyanonitrosyl ferrate (III)
c) sodium nitroferricyanide
d) sodium nitroferrocyanide

Answer: b

Question: The most stable system for a chelate is
a) five fused cyclic system
b) four fused cyclic system
c) three fused cyclic system
d) two fused cyclic system

Answer: a

Question: Write the formula for the coordination compund dichloridobis (ethane-1, 2-diamine) platinum(IV) nitrate
a) [PtCl₂(en)₂](NO₃)₂
b) [PtCl₂ (NO₃)₂](en)₂
c) [Pt(en)₂(NO₃)]Cl₂
d) None of these

Answer: a

Question: [Co(NH₃)₅SO₄ ]Br and [Co(NH₄)₅Br]SO₄ are
a) linkage isomers
b) coordination isomers
c) ionisation isomers
d) solvate isomers

Answer: c

Question: Which one of the following has an optical isomer ?
(en = ethylenediamine)
a) [Zn(en)(NH₃)₂ ]²⁺
b) [Co(en)₃]³⁺
c) [Co(H²O)⁴(en)]³⁺
d) [Zn(en)₂]²⁺

Answer: b

Question: Which type of ligand is contained in linkage isomerism?
a) Unidentate
b) Bidentate
c) Polydentate
d) Ambidentate

Answer: d

Question: Which of the following complex ions is diamagnetic in nature?
a) [CoF⁶]^3–
b) [NiCl₄]²⁻
c) [Ni(CN)₄]²⁻
d) [CuCl₂]²⁻

Answer: c

Question: The magnetic moment of Ni2+ ion (atomic number of Ni = 28) in BMunit is
a) 1.73
b) 4.81
c) 5.96
d) 2.84

Answer: d

Question: Iron carbonyl, Fe(CO)₅ is
a) trinuclear
b) mononuclear
c) tetranuclear
d) dinuclear

Answer: b

Question: In tetrahedral complexes, low spin complexes are not formed.
a) Δ_o > P
b) Δ_o < P
c) Δ_o = P
d) None of these

Answer: b

Question: Which of the following complex ions has electrons that are symmetrically filled in both t_2g and e_g orbitals?
a) [FeF₆]³⁻
b) [Mn(CN)₆]⁴⁻
c) [CoF₆]³⁻
d) [Co(NH₃)₆]²⁺

Answer: a

Question: Which of the following has square planar geometry?
a) [CoCl₄]²
b) [FeCl₄]²⁻
c) [NiCl₄]²⁻
d) [PtCl₄]²⁻

Answer: d

Question: An example of a sigma bonded organometallic compound is
a) ruthenocene
b) Grignard’s reagent
c) ferrocene
d) cobaltocene

Answer: b

Question: For lead-poisoning, the antidote used is
a) white of an egg
b) cis-platin
c) nickel
d) EDTA

Answer: d

1. Define the term coordination compound?

 

2. Write the names of counter ions in

 

(i) Hg [Co (SCN)₄] and (ii) [Pt(NH₃)₄] Cl₂.

 

3. Write the oxidation state of nickel in [Ni(CO)₄]

 

4. What is the coordination number of central atom in [Co(C₂O₄)₃]^3–?

[Ans. : 6]

 

5. What is the coordination number of iron in [Fe (EDTA)]^– ?

[Ans. : 6]

 

6. Write the name of a complex compound used in chemotherapy.

[Ans. : Cis–Platin. [Pt(NH₃)₂ Cl₂]

 

7. Name the compound used to estimate the hardness of water volumetrically.

 

8. Give the IUPAC name of [Pt Cl₂ (NH₂CH₃) (NH₃)₂] Cl.

 

9. How many geometrical isomers are possible for the tetrahedral complex [Ni(CO)₄].

[Ans. : No isomer, as the relative positions of the unidentate ligands attached to the central metal atom are same with respect to each other].

 

10. Arrange the following in the increasing order of conductivity in solution.

 Cl –, NH₃, I –, CO, en.

12. Write I.U.P.A.C. name of Tollens’ reagent.

13. Which is more stable? K3[Fe(CN)₆] or K4[Fe(CN)₆]

14. Calculate the overall dissociation equilibrium constant for the [Cu(NH3)4]2+ ion. Given that overall stability constant (4) for this complex is 2.1 × 10^13.
[Ans. : 4.7 × 10^–14]

15. What is a chelate ligand? Give one example.

16. Write the I.U.P.A.C. name of Li[AlH4].

17. Name one homogeneous catalyst used in hydrogenation of alkenes.

18. Name the types of isomerism shown by coordination entity : [CrCl₂(Ox)₂]^3–

19. [Ti(H₂O)₆]Cl₃ is coloured but on heating becomes colourless. Why?

20. Write the IUPAC name of ionization isomer of [Co(NH₃)₅(SO₄)] Br

21. Write the formula and the name of the coordinate isomer of [Co(en)3] [Cr(CN)₆].
[Ans. : [Cr(en)₃] [Co(CN)₆] Tris- (ethane –1, 2, diammine) chromium (III) hexacyanocobaltate (III)]

SA(I) TYPE QUESTIONS (2 - MARK QUESTIONS)

22. Write two differences between a double salt and a coordination compound with the help of an example of each.

23. Mention the main postulates of Werner’s Theory.

24. Define (a) Homoleptic and (b) Heteroleptic complexes with the help of one example of each.

25. In the following coordination entity : [Cu(en)₂]²⁺

(a) Identify the ligand involved and

(b) Oxidation state of copper metal.

27. Calculate the magnetic moments of the following complexes :

(i) [Fe(CN)₆]^4– (ii) [CoF₆]^3–

28. Explain the following :

(a) [Fe(CN)₆]^3– is an inner orbital complex whereas [FeF₆]^3– is an outer orbital complex.

 

(b) NH₃ acts as complexing agent but NH⁴⁺ does not.

29. What type of structural isomerism is represented by the following complexes:
(a) [Mn(CO)₅(SCN)] and [Mn(CO)₅(NCS)]
(b) [Co(NH₃)₅(NO₃)] SO₄

30. How are complex compounds applicable in (a) electroplating of silver, gold or other noble metals (b) in photography.

31. Explain on the basis of Valance Bond Theory that diamagnetic [Ni(CN)₄]^2– has square planar structure and paramagnetic [NiCl₄]^2– ion has tetrahedal geometry.

23. Explain as to how the two complexes of nickel [Ni(CN)₄]^2– and Ni(CO)₄ have different structures but do not differ in their magnetic behaviours. (At. no. of Ni = 28).

34. Draw the structures of geometrical isomers of the coordination complexes– [Co(NH3)3Cl3] and [CoCl2(en)2]+

35. Write the IUPAC name of the complexes :
(a) [NiCl₂ (PPh₃)₂] (b) [Co(NH₃)₄ Cl(NO₂)] Cl
(c) K[Cr(H₂O)₂ (C₂O₄)₂]
[Hint. : (a) Dichloridobis (triphenylphosphine) nickel (II);

36. Using IUPAC norms write the formulae for the following :
(a) Terabromidocuprate (II)
(b) Pentaamminenitrito–O– Cobalt (III)

37. How does EDTA help as a cure for lead poisoning?
[Ans. : Calcium in Ca–EDTA complex is replaced by lead in the body. The more soluble complex lead-EDTA is eliminated in urine].

37. A complex is prepared by mixing CoCl₃ and NH₃ in the molar ratio of 1:4.
0.1 m solution of this complex was found to freeze at –0.372°C. What is the formula of the complex?
K_f of water = 1.86°C/m
[Hint : ΔT_f = i K_f × m = i x 1.86 x 0.1
ΔT_f(obs) = 0.373°C
This means each molecule of complex dissociates into two ions.
Hence the formula is i = 2

38. The [Mn(H₂O)₆]²⁺ ion contains five unpaired electrons while [Mn(CN)₆]^4– ion contains only one unpaired electron. Explain using Crystal Field Theory:

SA (II) TYPE QUESTIONS (3 - MARK QUESTIONS)

39. Account for the following —
(i) [NiCl₄]^2– is paramagnetic while [Ni(CO)₄] is diamagnetic though both are tetrahedral.
(ii) [Fe(H₂O)₆]³⁺ is strongly paramagnetic whereas [Ni(NH₃)₆]²⁺ weakly paramagnetic.
(iii) [Co(NH₃)₆]³⁺ is an inner orbital complex whereas [Ni(MH₃)₆]²⁺ is in outer orbital complex.

40. Compare the following complexes with respect to their shape, magnetic behaviours and the hybrid orbitals involved.
(a) [CoF₆]^3–
(b) [Cr(NH₃)₆]³⁺
(c) [Fe(CN)₆]^4–
[Atomic Number : Co = 27, Cr = 24, Fe = 26]

41. Draw the structure of
(a) cis-dichloridotetracyanochromate (II) ion
(b) mer-triamminetrichloridocobalt (III)
(c) fac-triaquatrinitrito–N–cobalt (III)

42. Name the central metal atom/ion present in (a) Chlorophyll (b) Haemoglobin (c) Vitamin B-12.
[Ans. : (a) Mg (b) Fe; (c) Co.]

43. A metal complex having composition Cr(NH₃)₄ Cl₂Br has been isolated in two forms ‘A’ and ‘B’. The form ‘A’ reacts with AgNO₃ solution to give white precipitate which is readily soluble in dilute aqueous ammonia, whereas ‘B’ gives a pale yellow precipitate which is soluble in concentrated ammonia solution. Write the formula of ‘A’ and ‘B’. Also mention the isomerism which arises among ‘A’ and ‘B’.
[Hint : A = [Cr(NH₃)₄ BrCl] Cl; B = [Cr(NH₃)₄Cl₂] Br are ionisation isomers].

44. Write the limitations of Valence Bond Theory.

45. Draw a sketch to show the splitting of d-orbitals in an octahedral crystal field state for a d4 ion. How the actual electronic configuration of the split d-orbitals in an octahedral crystal field is decided by the relative values of Δ⁰ and pairing energy (P)?

46. For the complex [Fe(en)₂Cl₂]Cl identify
(a) the oxidation number of iron.
(b) the hybrid orbitals and the shape of the complex.
(c) the magnetic behaviour of the complex.
(d) the number of geometrical isomers.
(e) whether there is an optical isomer also?
(f) name of the complex. [At. no. of Fe = 26]

48. A chloride of fourth group cation in qualitative analysis gives a green coloured complex [A] in aqueous solution which when treated with ethane –1, 2-diamine (en) gives pale yellow solution [B] which on subsequent addition of ethane –1, 2-diamine turns to blue/purple [C] and finally to violet [D]. Identify [A], [B], [C] and [D] complexes,
[Hint. : Nickel, [A] = [Ni(H2O)₆]²⁺ ; [B] = [Ni(H₂O)₄ (en)]^{2+ ;} [C] = [Ni(H₂O)₂ (en)₂]²⁺ ; [D] = [Ni(en)₃]²⁺.