Coordination Compounds Mock Test – Class 12 Chemistry

1. An analyst adds a ligand that forms a stable soluble complex with an interfering metal ion . The target ion is then precipitated without precipitation of . The role of is best described as:

2. Which sequence correctly pairs coordination number and a representative geometry?

3. A weak-field octahedral complex described by hybridisation contains:

4. For high-spin octahedral , the CFSE and magnetic moment are:

5. A compound of composition gives two moles of per mole of compound and produces three ions per formula unit on ideal dissociation. Its formula is:

6. A -electron transition occurs when the energy of the absorbed photon satisfies:

7. Assertion: Simple valence bond theory can predict that two complexes have different numbers of unpaired electrons but may not explain the energetic origin of that difference.
Reason: The theory assigns pairing and hybridisation without quantitatively comparing orbital splitting energy with pairing energy.

8. Which set contains only correctly classified ligand–donor-atom pairs?

9. 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:

10. Regarding cyanide extraction of silver, the valid statement is:

11. 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.

12. Complex is a diamagnetic four-coordinate nickel(II) complex that absorbs at a shorter wavelength. Complex is a paramagnetic four-coordinate nickel(II) complex with two unpaired electrons and absorbs at a longer wavelength. Which assignment is most consistent?

13. Assertion: The biological role of a coordination compound cannot be predicted from the identity of the metal alone.
Reason: The surrounding ligand framework controls geometry, electronic environment, binding sites, and chemical reactivity of the metal centre.

14. Consider the following statements about limitations of simple valence bond theory.
Statement I: It does not quantitatively explain the colour of coordination compounds.
Statement II: It gives no satisfactory energetic account of why some complexes are high spin and others low spin.
Statement III: It does not calculate crystal-field stabilisation energy.
Statement IV: It cannot represent any coordination geometry.
The valid statements are:

15. The oxidation state and -electron configuration of cobalt in are:

16. A claim states that only negatively charged ions can satisfy the secondary valency of a metal. The best correction is:

17. A metal ion can form a octahedral complex without prior electron pairing because:

18. A metal ion has a configuration. Under strong-field conditions, its electrons pair in three inner orbitals, leaving two inner orbitals vacant. The expected hybridisation, geometry, and number of unpaired electrons are:

19. Two compounds have the same overall composition, but a bromido ligand inside the coordination sphere of one compound is a bromide counter ion in the other. Before any stereochemical counting, the pair should be classified as:

20. A coordination compound is known to be octahedral, low spin, coloured, and stabilised by before pairing terms are considered. Which theory provides the most direct unified explanation of the last three properties?

21. Study the proposed properties of fully deprotonated EDTA.

The inconsistent row is:

22. The tetrahedral CFSE of a ion with configuration is:

23. Cis- and trans- contain cobalt in the same oxidation state because:

24. Use the arrangement described below: an octahedral metal centre is bonded to two ligands and two ligands. The number of ligand molecules and the coordination number are respectively:

25. Which pair represents the geometrical isomers of ?

26. The complete electronic description of tetrahedral is:

27. Separate aqueous solutions of Mohr’s salt and are treated with a reagent that tests for free . The expected observation is that:

28. Assertion: A octahedral complex is called an inner-orbital complex.
Reason: The two orbitals used in hybridisation belong to the shell.

29. Study the classification of the following metal carbonyls.

The inconsistent row is:

30. In the coordination entity , the central species and the surrounding ligands are respectively:

31. Which comparison is generally valid for analogous complexes of metals from the same group?

32. In an octahedral complex of the type , the facial form is obtained when:

33. Assertion: A ligand that binds through two donor atoms to the same metal can form a chelate ring.
Reason: The two donor atoms and the part of the ligand connecting them provide a closed path through the metal centre.

34. The different geometries of and , despite both having coordination number , are respectively:

35. Consider the following statements about cisplatin.
Statement I: It is a platinum coordination compound used in cancer chemotherapy.
Statement II: Its platinum centre is square planar.
Statement III: Its cis geometry is important for its biological activity.
Statement IV: Its therapeutic use proves that platinum compounds are harmless at every dose.
The valid statements are:

36. Select the valid description of :

37. In an octahedral complex , where is an ordinary bidentate ligand, cis-trans isomerism arises because:

38. 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:

39. Consider the following statements about Werner’s valencies.
Statement I: Primary valency is generally satisfied by negative ions.
Statement II: Secondary valency may be satisfied by neutral molecules or negative ions.
Statement III: Secondary valency is always ionisable in aqueous solution.
The valid statements are:

40. Assertion: A complex containing three bidentate ligands is often more stable than a comparable complex containing six similar monodentate ligands.
Reason: Replacement by the bidentate ligands can increase the number of free particles and produce a favourable entropy contribution.

41. Study the formula-name pairs.

The inconsistent row is:

42. Assertion: The chelate effect cannot be explained simply by saying that every individual bond made by a multidentate ligand is stronger than every bond made by a monodentate ligand.
Reason: Chelate stability also involves ring formation, reduced probability of complete ligand loss, and favourable entropy changes in many ligand-replacement equilibria.

43. A four-coordinate complex is experimentally diamagnetic. Another complex of the same metal ion is paramagnetic with two unpaired electrons. The most consistent geometries of the two complexes are respectively:

44. Solvate isomerism arises when:

45. Samples and have the same composition . Sample gives with , whereas sample gives with . The formulas of and are respectively:

46. Assertion: is paramagnetic even though it is a low-spin complex.
Reason: Its configuration contains one singly occupied orbital.

47. Ignoring water of crystallisation, the number of moles of simple ions produced by complete dissociation of of Mohr’s salt, , is:

48. Both and have coordination number , yet their geometrical-isomerism behaviour may differ because:

49. A coordinated sulfate ion and an external bromide ion exchange positions to produce a second compound with the same overall elemental composition. The change represents:

50. Assertion: A large octahedral splitting energy can produce a low-spin complex.
Reason: When , pairing in costs less energy than placing an electron in .