Chemistry

Coordination Chemistry

319 Questions

Coordination chemistry focuses on coordination compounds, their structures, and their magnetic properties. The questions cover primary and secondary valencies, ligand types, and geometries of complexes. This topic is heavily tested in chemistry competitive exams and requires a good grasp of molecular structures.

primary and secondary valencycomplex geometriesligand field theorymagnetic properties of complexesisomerism in complexes

Coordination Chemistry Questions

Multiple choice

Which of the following statements is/are incorrect? A. The complex ion trans-dichloro bis (ethylenediamine) rhodium (III) is optical active. B. Secondary valancies are non-directional whereas primary valencies are directional. C. Both geometrical and optical isomerisms are shown by [Co(en)2Cl2]+.

  1. Only A

  2. Only B

  3. Both 1 and 2

  4. Only C

  5. Both 2 and 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct because trans-dichloro bis (ethylenediamine) rhodium(III) is symmetrical and therefore, is optically inactive and according to Werner’s theory, secondary valancy is directional whereas primary valency is non-directional.

Multiple choice

Geometrical isomerism in coordination compounds is exhibited by __________.

  1. only tetrahedral complexes

  2. square planar and tetrahedral complexes

  3. square planar and octahedral complexes

  4. tetrahedral and octahedral complexes

  5. square planar, tetrahedral and octahedral complexes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Geometrical isomerism in coordination compounds is exhibited by square planar and octahedral complexes because they have centre of symmetry. Thus, this option is correct.

Multiple choice

Assertion: Ethylenediaminetetraacetate ion forms an octahedral complex with the metal ion. Reason: It has six donor atoms which coordinate simultaneously with metal ion.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is not the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct because EDTA has six donor atoms which coordinate with metal ion.

Multiple choice

Which of the following statements is incorrect? A. βn is equal to the product of K1, K2, K3 …… Kn. B. K1, K2, K3 …… Kn are called stepwise stability or formation constants. C. βn = K1 + K2 + K3 …… Kn.

  1. Only A

  2. Only B

  3. Only C

  4. A and B

  5. A and C
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is correct because the overall stability constant (βn) is equal to the product of stepwise stability constants K1, K2, K3 ……Kn, i.e.,  βn = K1 ˣ K2 ˣ K3 ……Kn.

Multiple choice

Match the list I (coordination compounds) with list II (isomers):

 
List - I
List - II
(i) [Co(NH3)5Br]SO4 and [Co(NH3)5SO4]Br a. Linkage isomers
(ii) [Co(NH3)6][Cr(CN)6] and [Cr(NH3)6][Co(CN)6] b. Ionisation isomers
(iii) [Cr(H2O)5Cl]Cl2.H2O and [Cr(H2O)4Cl2]Cl.2H2O c. Polymerisation isomers
(iv) [Pt(SCN)6](NH42 and [Pt(NCS)6](NH42 d. Coordination isomers
(v) [Co(NH3)6][Co(NO2)6] and [Co(NH3)3(NO2)3] e. Hydration isomers

  1. i - b, ii - d, iii - e, iv - a, v - c

  2. i - a, ii - d, iii - e, iv - b, v - c

  3. i - b, ii - c, iii - e, iv - a, v - d

  4. i - a, ii - c, iii - b, iv - d, v - e

  5. i - d, ii - e, iii - c, iv - b, v - a
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct because all the items present in list I are correctly matched with list II.

Multiple choice

Which among the following acts as a bidentate chelating ligand?

  1. 2,2'-Bipyridine

  2. Biphenyl

  3. Borneol

  4. Biuret
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

2,2'-Bipyridine is an organic compound with the formula (C10H8N2). It is an important isomer of the bipyridine family. It is a bidentate chelating ligand, forming complexes with many transition metals.

Multiple choice

The porphyrin ring of a heme group consists of central atom of

  1. magnesium

  2. iron

  3. copper

  4. nitrogen
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The heme group is a prosthetic group containing a porphyrin ring with a central iron atom (Fe2+). This iron is crucial for oxygen binding in hemoglobin and myoglobin, and for electron transfer in cytochromes.

Multiple choice

The CFSE for octahedral complexes of Fe3+ in a weak field and strong field ligand systems are ____________ respectively.
    • 4Dq, - 20 Dq

  2. 0, - 20 Dq
    • 4Dq, - 20 Dq+2P
    • 12Dq, - 20 Dq+2P

  5. 0, - 20 Dq+2P
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

In a weak field ligand system, the electron filling of splitting of d-orbital corresponds to Hund’s rule, followed by pairing. In strong field ligand system, the electron filling of splitting of d-orbital corresponds to pairing at initial stage. For Fe3+ electronic configuration is d5. For d5 in weak field ligand system, CFSE = 3 (- 4) + 2 (6) = - 12 + 12 = 0 Dq (All electrons is unpaired, 3 in t2g and 2 in eg) For d5 in strong field ligand system, CFSE = 5 (- 4) + 0 = - 20 Dq + 2P
(two paired electrons and one electron is unpaired in t2g and 0 electron in eg orbital) Hence, the CFSE for octahedral complexes of Fe3+ in a weak field and strong field ligand systems are 0 and -20 Dq+2P respectively.