Coordination Compound MCQs and Important Questions

Coordination Compound MCQs and Important Questions

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

(a) [Co(CN)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+

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

(a) 1:3 electrolyte                (b) 1:2 electrolyte                  (c) 1:1 electrolyte                   (d) 3:1 electrolyte

3. When 1 mol CrCl3⋅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) [CrCl(H2O)5]Cl2⋅H2O          (d) [Cr(H2O)6]Cl3

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

(a) Diamminedichloridoplatinum (II)                             (b) Diamminedichloridoplatinum (IV)

(c) Diamminedichloridoplatinum (0)                             (d) Dichloridodiammineplatinum (IV)

5. The stabilization of coordination compounds due to chelation is called the chelate effect. Which of the following is the most stable complex species?

(a) [Fe(CO)5]                         (b) [Fe(CN)6]3–                        (c) [Fe(C2O4)3]3–                         (d) [Fe(H2O)6]3+

6. 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-

7. 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) ionisation isomers        (d) geometrical isomers

8. The compounds [Co(SO4)(NH3)5]Br and [Co(SO4)(NH3)5]Cl represent

(a) linkage isomerism                                                     (b) ionisation isomerism       

(c) coordination isomerism                                           (d) hydrate isomerism

9. 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

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Word File of Coordination Compounds MCQs, Assertion Reasoning and Case Study

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

(a) NO                                     (b) NH4+                            (c) NH2CH2CH2NH2               (d) CO

11. 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

12. 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)

13. 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-

14. The formula of the complex dichloridobis(ethane-1,2-diamine)platinum(IV) chloride

       (a) [PtCl2(en)] Cl2                  (b) [PtCl2(en)2]Cl2                (c) [PtCl2(en)] Cl3                (d) [Pt2Cl2(en)2]Cl4

15.One mole of CrCl3.6H2O compound reacts with excess AgNO3 solution to yield two moles of AgCl(s). The structural formula of the compound is

(a) [Cr(H­2O)5Cl]Cl2.H2O         (b) [Cr(H2O)3Cl3].3H2O        (c) [Cr(H2O)4Cl2]Cl.2H2O          (d) [Cr(H2O)­6 Cl3]

16. IUPAC name of the compound [Ag (NH3)2] [Ag (CN)2]

(a) Diamminesilver(II) dicyanidosilver(II)                  (b) Diamminesilver(I) dicyanidoargentate(II)                    (c) Diamminesilver(I) dicyanidoargentate(I)            (d) Diamminesilver(II) dicyanidoargentate(II)

17. The formula of the complex Triamminetrinitrtito-O-cobalt(III) is

(a) [Co (NH3)3(NO2)3]2+          (b) [Co (NH3)3(NO2)3]3+       (c) [Co (NH3)3(NO2)3]          (d) [Co (NH3)3(ONO)3]

18. The complex ions [Co (NH3)5(NO2)]2+ and [Co (NH3)5 (ONO)]2+ are called
(a) Ionization isomers        (b) Linkage isomers       (c) Co-ordination isomers    (d) Geometrical isomers

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

(a)tetraaquadiamminecobalt (II)chloride                           (b) tetraaquadiamminecobalt (III)chloride

(c)diamminetetraaquacobalt (II)chloride                           (d)diamminetetraaquacobalt (III)chloride

20. 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)

Coordination Compound Assertion Reason Questions

(a)Assertion and reason both are correct statement and reason is correct

     explanation for assertion.

(b) Assertion and reason both are correct statement and reason is not correct

     explanation for assertion.

(c)Assertion is correct statement but reason is wrong statement.

(d) Assertion is wrong statement but reason is correct statement.

1. Assertion: Tetrahedral complexes don’t show geometrical isomerism.
    Reason: The relative positions of the ligands in the tetrahedral complexes are the same concerning each other.

2. Assertion: [Co(NH3)3Cl2] does not give a white precipitate with AgNO3 solution.
    Reason:   Chlorine is not present in the ionising sphere.

3. Assertion: [Co(NH3)3(NO3)3] does not show any optical isomerism.
    Reason: It has a plane of symmetry.

4. Assertion: The complex [Ni(CN)4] is diamagnetic in nature.
    Reason: ‘Ni’ ion in the complex is dsp2 hybridized.

5. Assertion: Potassium ferrocyanide is diamagnetic whereas potassium ferricyanide is paramagnetic.
    Reason:   Crystal field splitting in ferrocyanide ion is greater than that in ferricyanide ion.
6. Assertion: Linkage isonerism arises in coordination complexes containing an ambidentate ligand.
    Reason:   Ambidentate ligand has two donor atoms.

7. Assertion: The ligands nitrito-N and nitrito-O are ambidentate ligands.
    Reason   : The ligands give linkage isomers.

8. Assertion: [Fe(H2O)5NO2]SO4 is Paramagnetic.
    Reason   : The Fe atom in [Fe(H2O)5NO2]SO4 has three unpaired electrons.

9. Assertion: [Cu(NH3)4]2+ is sp3 hybridised tetrahedral complex.
    Reason   : [Cu(NH3)4]2+is paramagnetic in nature.

10.Assertion: [Cu(en)2]2+ is more stable than [(Cu(NH3)4]2+
     Reason:    Ethylene diamine is a chelating ligand.

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Coordination Compound Case Study based Questions

Read the passage and answer the following questions

1. Co-ordination compounds are widely present in the minerals, plant and animal worlds and are known to play many important functions in the area of analytical chemistry, metallurgy, biological systems, and medicine. Alfred Werners theory was postulated using two types of linkages (primary and secondary) by a metal atom or ion in a coordination compound. He predicted the geometrical shapes of a large number of coordination entities using the property of isomerism. The valence bond theory explains the formation, magnetic behaviour, and geometrical shapes of coordination compounds. The Crystal field Theory explains the effect of different crystal fields on the degeneracy of d-orbital energies of the central metal atom or ion.

(a)Using Valence Bond Theory, predict the geometry and magnetic nature of

     (i) [Ni(CO)4]      (ii) [Fe(CN)63-     (Atomic number of Ni= 28, Fe =26)

OR

   Give reason:

   (i)Low spin tetrahedral complexes are not formed.

   (ii)[Co(NH3)6]3+ is an inner orbital complex whereas [Ni(NH3)6]2+ is an outer orbital complex.

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

(c)When a coordination compound NiCl2.6H2O is mixed with AgNO3 solution, 2 moles of AgCl are precipitated per mole of the compound. write the structural formula of the complex and secondary valency for Nickel ion.

2. According to Valence Bond Theory, the metal atom or ion under the influence of ligands can use its inner or outer d-orbitals for hybridization to yield a set of equivalent orbitals of definite geometry such as octahedral, tetrahedral, square planar and so on. These hybridized orbitals are allowed to overlap with ligand orbitals that can donate electron pairs for bonding.

(a) what is the coordination number of Co in [Co(en)3]3+?

OR

      Is [Co(NH3)6]3+ complex diamagnetic or paramagnetic?

(b) Why [Co(en)3]3+ is more stable than[Co(NH3)6]3+?

(c) Give reason for the following.

      (i)[Ni(CN)4]2- is an inner orbital complex.

      (ii)[Fe(H2O)6]2+ is paramagnetic in nature.

3. Werner’s theory of complex compounds says every metal atom or ion has primary valency (oxidation state) which is satisfied by -vely charged ions, ionisable where secondary valency (coordination number) is non-ionisable, satisfied by Iigands (+ve, -ve, neutral) but having lone pair. Primary valency is non-directional, secondary valency is directional. Complex compounds are name according to IUPAC system. Valence bond theory helps in determining shapes of complexes based on hybridisation, magnetic properties, outer or inner orbital complex.Complex show ionisation, linkage, solvate and coordination isomerism also called structural isomerism. Some of them also show stereoisomerism i.e. geometrical and optical isomerism. Ambidentate ligand are essential to show linkage isomerism. Polydentate Ligands form more stable complexes then unidentate Iigands. There are called chelating agents. EDTA is used to treat lead poisoning, cis-platin as anticancer agents. Vitamin B12 is complex of cobalt. Hemoglobin, oxygen carrier is complex of Fe2+ and chlorophyll essential for photosynthesis is complex of Mg2+.


(a) One mole of CrCI3 . 6H2O reacts with excess of AgNO3 to yield 2 mole of AgCI. Determine the Molecular formula of complex, do the IUPAC name of the compound.

OR

(a) What is hybridization, shape and magnetic properties of [CoF6]3- [Co = 27].
(b) Out [Fe(CO)5], [Fe(CO4 )3]3-, [Fe(H2O6)3+, [Fe(CN)6]3-, which is most stable?

(c) Out Cis – [Pt(en)2 CI2 ]2+ and trans (Pt(en)2CI2 )2+ which one shows optical isomerism?

4. The oxidation number ofthe central atom in a complex is defined as the charge it would carry if all the ligands are removed along with the electron pairs that are shared with the central atom. Similarly, the charge on the complex is the sum of the charges of the constituent pairs. i.e the sum of the charges on the central metal ion and its surrounding ligands. Based on this, the complex is called neutral if the sum of the charges of the constituents is equal to zero. However, for an anionic or cationic complex, the sum of the charges of the constituents is equal to the charge on the co-ordination sphere.

(a) What is the secondary valency of Co in [Co(NH3)4Cl2]+?

(b) What type of isomerism is shown by the complex [Cr(H2O)6]Cl3 and [Cr(H2O)5Cl]Cl2.H2O?

(c) Write electronic configuration of d4 ion based on crystal field theory when (a) ∆o < P (b) ∆o > p

OR

(c) Find the oxidation state and co-ordination number of the central ion in [Co(H2O)(CN)(en)2]2+

5. To explain bonding in coordination compounds various theories were proposed. One of the important theories was valence bond theory. According to this theory, the central metal ion in the complex makes available of empty orbitals for the formation of coordinate bonds with suitable ligands. The appropriate atomic orbitals of the metal hybridize to give a set of equivalent orbitals of definite geometry. The d-orbitals involved in the hybridization may be either inner d-orbitals i.e., (n – 1) d or outer d-orbitals i.e., nd. For example, CO3+ forms both inner orbital and outer orbital complexes. With ammonia it forms [Co(NH3)6]3+ and with fluorine it forms [CoF6]3- 

(a) Why Nickel does not form low spin octahedral complex.

(b) Why [Co(NH3)5]3+ is an inner orbital complex while [Ni(NH3)6]2+ is an outer orbital complex.

(c) Predict the hybridization, geometry and magnetic behavior of [CoF6]3

                                                             OR

(c) Predict the hybridization, geometry and magnetic behavior of [Fe(CN)6]3

6. The oxidation number of the central atom in a complex is defined as the charge it would carry if all the ligands are removed along with the electron pairs that are shared with the central atom. Similarly, the charge on the complex is the sum of the charges of the constituent parts i.e the sum of the charges on the central metal ion and its surrounding ligands. Based on this, the complex is called neutral if the sum of the charges of the constituents is equal to zero. However, for an anion or cationic complex, the sum of the charges of the constituents is equal to the charge on the coordination sphere. Based on the above information, answer the following questions.

(a) Define ambidentate ligand. Give an example.

(b) What type of isomerism is shown by [Co(NH3)5Cl]SO4 and [Co(NH3)5 SO4] Cl?

(c) What is chelate effect. How it affects the stability of complex?

OR

(c) Find the coordination number and oxidation number of Cr in Na3[Cr(C2O4)3].

7. Coordination compounds exhibit an array of colours which can be explained through the principles of Crystal field theory. This theory provides a framework for understanding how the interaction between the metal ion and surrounding ligands affects the metal, leading to the absorption of specific wavelengths of light. The colour for a complex is actually the complementary colour of light absorbed.

Coodination complexColour
[Fe(CN)6]3-Yellow
[Ti(H2O)6]3+Violet
[Ni(CO)4]Colourless
[Cu(NH3)4]2+Deep blue

Study the above data and answer the following questions.

(a) (i) How many unpaired electrons are there in [Ni(CO)4]?

      (ii) Why does [Ni(CO)4] appear colourless?

(b) According to Crystal field theory, why does the colour of a coordination complex depend on the nature of its ligands?

(c) What is the magnetic behaviour shown by [Ti(H2O)6]3+

OR

(c) [Cu(NH3)4]2+ has how many unpaired electrons in 3d-orbital?

8. Complex compounds play an important role in our daily life. These compounds contain central metal and ligands. Ligands can be neutral or negatively charged. Ligands can be differentiated on the basis of the number of donor sites which is simply called as denticity. It can be monodentate, bidentate, polydentate , ambidentate ligands. Polydentate ligands are more stable than monodentate ligands. Complex compound are named according to IUPAC system. Many approaches have been put forth to explain the nature of bonding in complex compounds. These are valence bond theory(VBT), Crystal field theory(CFT).

Based on above information, answer the followings.

(a) What is the oxidation state of Cu in [Cu(NH3)4Cl2]?

(b) What is the IUPAC name of the complex [Ni(NH3)6]Cl2?

(c) What is the magnetic property and number of unpaired electron in [Co(NH3)6]3+?

OR

(c) What is the hybridization and geometry of [Co(NH3)6]3+?

9. The oxidation number of the central atom in a complex is defined as the charge it would carry if all the ligands are removed along with the electron pairs that are shared with the central atom. Similarly, the charge on the complex is the sum of the charges of the constituent parts i.e the sum of the charges on the central metal ion and its surrounding ligands. Based on this, the complex is called neutral if the sum of the charges of the constituents is equal to zero. However, for an anion or cationic complex, the sum of the charges of the constituents is equal to the charge on the coordination sphere.

Based on the above information, Answer the following questions.

(a) What is the secondary valency of Co in [Co(NH3)4Cl2]+?

(b) What type of isomerism is shown by [Cr(H2O)6]Cl3?

(c) Write the electronic configuration of d4 ion on the basis of CFT when

                                                (i) ∆O > P    (ii)  ∆O < P

OR

(c) Find the oxidation state and coordination number of central metal ion in [Co(H2O)(CN)(en)2]2+.

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