Coordination Compounds Mock Test – Class 12 Chemistry

1. In , the oxidation state and -electron configuration of nickel are respectively:

2. Study the ligand comparisons made for the same metal ion under similar conditions.

The inconsistent row is:

3. For the overall equilibrium

the equilibrium concentrations are , , and . The value of is:

4. The naming order of differs from that of because:

5. A water sample requires of EDTA for complete titration. Assuming all hardness is expressed as , what is the hardness in ? Use .

6. Two entities are compared: and . The sound classification is:

7. and have the same oxidation state and coordination number but different magnetic properties because:

8. Which spin-only result is expected for a diamagnetic coordination complex?

9. A student claims that a complex cannot absorb electromagnetic radiation because all its orbitals are filled. Which correction is best?

10. Assertion: The metal in is named platinum rather than platinate.
Reason: The complete coordination entity is neutral, and the -ate ending is reserved for anionic coordination entities.

11. Assign the name, spin state, and magnetic property of in the standard strong-field treatment:

12. Study the donor-mode table.

The inconsistent row is:

13. A student claims that ligand identity is the only factor needed to determine . Which observation best disproves this claim?

14. An entity contains one bidentate ligand, one bidentate oxalato ligand, and two monodentate ligands. Its coordination number and total number of ligand particles are respectively:

15. Assertion: donation and back-bonding in a metal carbonyl reinforce one another.
Reason: donation increases electron density at the metal for back donation, while back donation removes some metal electron density and allows continued ligand-to-metal donation.

16. After gold has been converted into , addition of zinc can recover metallic gold according to:

17. Consider the following statements about metal–carbonyl back-bonding.
Statement I: It involves filled metal orbitals.
Statement II: It populates antibonding orbitals of .
Statement III: It increases the internal carbon–oxygen bond order.
Statement IV: It contributes to strengthening of the metal–carbon bond.
The valid statements are:

18. Assertion: A tetrahedral complex can be paramagnetic even though a square-planar complex may be diamagnetic.
Reason: The tetrahedral description does not require the pairing needed to make an inner orbital vacant for square-planar hybridisation.

19. Assertion: A labile complex can still be thermodynamically stable.
Reason: The term labile describes rapid ligand substitution, whereas thermodynamic stability describes the equilibrium tendency against dissociation.

20. In , the oxidation states of cobalt and chromium are:

21. Consider the following statements about coordination number and geometry.
Statement I: Coordination number is commonly associated with octahedral geometry.
Statement II: Coordination number always implies tetrahedral geometry.
Statement III: Metal configuration and ligand field can influence the geometry of a four-coordinate complex.
Statement IV: Coordination number counts ligand molecules rather than donor atoms.
The valid statements are:

22. Why can a strongly solvating solvent reduce the apparent tendency of a metal ion to form a particular ligand complex?

23. For the stepwise formation equilibrium

the constant measures:

24. Which observation correctly identifies cis-?

25. A weak-field ligand in a four-coordinate nickel(II) complex is replaced by a strong-field ligand. The product becomes diamagnetic. Which change is most consistent with the standard treatment?

26. The platinum centre in cisplatin follows the sequence:

27. Consider the following statements about tetrahedral coordination entities.
Statement I: A simple tetrahedral entity ordinarily has no cis–trans pair.
Statement II: All four positions of a regular tetrahedron are equivalent.
Statement III: Coordination number always implies tetrahedral geometry.
Statement IV: A tetrahedral entity containing four different ligands may be chiral.
The valid statements are:

28. The formula of potassium tris(oxalato)ferrate(III) is:

29. donation, back-bonding, and low-oxidation-state stabilisation in metal carbonyls are integrated by the statement:

30. Assertion: Connectivity should be checked before deciding whether a pair of coordination compounds shows geometrical isomerism.
Reason: Geometrical isomers must have the same metal–ligand connectivity and differ only in spatial arrangement.

31. Three octahedral complexes of the same metal are compared.
Complex contains ligand and absorbs at .
Complex contains a stronger-field ligand and absorbs at .
Complex is formed by oxidising the metal in , while retaining the same ligand and geometry, and absorbs at .
Which interpretation is most consistent with these observations?

32. Cisplatin is represented by the formula:

33. A sample of is resolved into fractions and . Fraction rotates plane-polarised light clockwise, while produces an equal rotation in the opposite direction under identical conditions. The fractions are:

34. A theory predicts that a complex is octahedral and paramagnetic but cannot account satisfactorily for its absorption wavelength. The theory being used is most likely:

35. A coordination entity contains ammine, aqua, and chlorido ligands. Ignoring multiplicative prefixes, the correct alphabetical order of the ligand names is:

36. Assertion: Simple crystal field theory has a limited ability to explain detailed spectral intensities.
Reason: The elementary electrostatic model does not fully include covalent orbital mixing and the detailed transition-probability factors.

37. A monodentate ligand is identified by its ability to:

38. Two samples have the formula . Each produces one mole of per mole with excess , but the samples have different colours and ligand arrangements. The observations indicate that the samples:

39. The coordination number of a central metal is determined by counting:

40. A homoleptic coordination entity contains:

41. The five orbitals of an isolated gaseous metal ion are described as degenerate because they:

42. The orbitals mixed during formation of four tetrahedrally directed hybrid orbitals are:

43. A student interprets to mean that two metal–ligand bonds are -type, one is -type, and three are -type. The correct interpretation is:

44. A hard metal ion such as is offered two otherwise comparable ligands, one coordinating through oxygen and the other through sulphur. Which interaction is generally favoured by the hard-soft compatibility principle?

45. Consider the following statements.
Statement I: A double salt has a definite composition in the crystalline state.
Statement II: A double salt necessarily remains as one complex ion in aqueous solution.
Statement III: A coordination compound can release counter ions while retaining its bracketed coordination entity.
The valid statements are:

46. A student assigns square-planar geometry and diamagnetism to , reasoning that every diamagnetic four-coordinate nickel compound must be square planar. The assignment should be evaluated as follows:

47. Complex is formed by a tridentate ligand and has . An analogous complex , formed from comparable monodentate donors, has . By what factor is formation of more strongly favoured according to these constants?

48. A six-coordinate complex contains a metal ion. Strong ligand-induced pairing leaves two inner orbitals vacant. Which set of properties is predicted by the standard valence bond treatment?

49. Complexes and both have the form and are compared under the same conditions. Their overall formation constants are and . Which conclusion is justified?

50. A student states that every complex containing must be an inner-orbital complex. The best correction is: