250+ TOP MCQs on Bonding in Coordination Compounds and Answers

Chemistry Problems for IIT JEE Exam on “Bonding in Coordination Compounds – 2”.

1. The crystal field theory considers the metal-ligand bond to be a _______ bond.
a) covalent
b) ionic
c) polar
d) hydrogen
Answer: b
Clarification: The CFT is an electrostatic model which considers the bond between metal ion and the ligand to be ionic arising due to the electrostatic interactions between them.

2. In CFT, which of the following ligands will be treated as point dipoles?
a) Cl
b) NO₂
c) CN
d) NO
Answer: d
Clarification: Anionic ligands are treated as point charges and neutral ligands are treated as point dipoles in crystal field theory.

3. Which of the following orbitals does not belong to t_2g orbitals?
a) d_xy
b) d_yz
c) d_xz
d) d_z²
Answer: d
Clarification: t_2g is a set of three d orbitals of lower energy in octahedral complexes. The two remaining d orbitals of higher energy form the e_g set.

4. Identify the correct order of increasing field strength of the ligands.
a) SCN^–, NH₃, NCS^–, CN^–
b) NCS^–, SCN^–, NH₃, CN^–
c) SCN^–, NCS^–, NH₃, CN^–
d) NCS^–, NH₃, SCN^–, CN^–
Answer: c
Clarification: According to the spectrochemical series, thiocyanate is weaker than isothiocyanate which is in turn weaker than amine and cyanide ligands.

5. By how much percentage does the energy of e_g orbitals increase by from the average field splitting energy in octahedral complexes?
a) 40%
b) 45%
c) 50%
d) 60%
Answer: d
Clarification: The energy of the two e_g orbitals will increase by (3/5)Δ_o, that is 60% of the average energy that separates the field in octahedral complexes.

6. Identify the correct order of decreasing field strength of the neutral ligands.
a) CO, en, NH₃, H₂O
b) CO, en, H₂O, NH₃
c) en, CO, NH₃, H₂O
d) en, CO, H₂O, NH₃
Answer: a
Clarification: According to the spectrochemical series, CO is the strongest ligand. The ligands en, amine and water are weaker than CO and their field strength decreases in that order.

7. Identify the correct relation between Δ_o and Δ_t, where Δ_o denotes crystal field splitting in octahedral complexes and Δ_t denotes crystal field splitting in tetrahedral complexes.
a) Δ_ot
b) Δ_o > Δ_t
c) Δ_o = Δ_t
d) Δ_o ≥ Δ_t
View Answer

Answer: b
Clarification: It has been observed that splitting energy in tetrahedral fields is considerably less than in octahedral complexes. To be precise, it has been found that Δ_t = (4/9) Δ_o.

8. Which of the following ligands is most likely to form high spin complexes in octahedral fields?
a) Cl^–
b) OH^–
c) C₂O₄^–
d) CN^–
Answer: a
Clarification: Cl- is the weakest field ligand in the given options. The splitting field Δ_o is small and the energy separation between the e_g and t_2g orbitals are narrower. Hence, the electrons tend to occupy the eg orbitals easily and are likely to have a greater number of half-filled orbitals.

9. What will be the electronic configuration of d⁵ in terms of t_2g and e_g in an octahedral field when Δ_o

a) t_2g⁵ e_g⁰
b) t_2g² e_g³
c) t_2g³ e_g²
d) t_2g⁰ e_g⁵
Answer: c
Clarification: When the field splitting is less than the pairing energy, the energy gap between the two sets of d orbitals is small. This allows the electrons to occupy the higher energy orbitals once the lower orbitals are singly occupied. Thus, the configuration will be t_2g³ e_g², with one electron in each orbital.

10. Tetrahedral fields can easily form low spin complexes.
a) True
b) False
Answer: b
Clarification: The splitting energy in tetrahedral fields is almost half of that of octahedral fields. Due to this, the orbital splitting energies are not very large, which makes it difficult for electron pairing and therefore low spin complexes are rarely formed.

11. Observe the orbital splitting diagram of a tetrahedral field and find the value of x.

a) 0.178
b) 0.267
c) 0.4
d) 0.44
Answer: a
Clarification: The value of x is asked in terms of Δ_o and not Δ_t. The t₂ orbitals is at an energy of (2/5) Δ_t above the average energy. This is equal to (2/5) times (4/9) Δ_o = 0.178Δ_o.

12. As the crystal field splitting energy in octahedral field increases, the wavelength of light absorbed _________
a) Increases
b) Decreases
c) Remains the same
d) May increase or decrease
Answer: b
Clarification: If Δ_o is less (as in weak field ligands), the excitation energy will be the smallest and the largest wavelength will be absorbed. On the other hand, Δ_o is high (as in strong field ligands), the excitation energy will be the largest and the smallest wavelength will be absorbed.

13. The complex [Co(H₂O)₆]³⁺ absorbs the wavelength of light corresponding to orange colour. Predict the colour of the coordination compound based on this information.
a) Red
b) Yellow
c) Blue
d) Colourless
Answer: c
Clarification: This is because of the concept of complementary colours. The colour of the complex is complementary to that which is absorbed and is generated from the wavelength that is left over.

14. Hexaaquatitanium(III) chloride is a coloured compound that loses its colour on heating.
a) True
b) False
Answer: a
Clarification: Heating the compound removes the water which is the ligand. In the absence of a ligand, crystal field splitting does not occur and hence the compound becomes colourless.

Chemistry Problems for IIT JEE Exam,