The d-and f-Block Elements Mock Test – Class 12 Chemistry

1. An unknown inner-transition ion is radioactive, forms strongly covalent complexes, changes colour appreciably with ligand substitution, and is paramagnetic. Which description is most consistent with these observations?

2. A graph plots moles of electrons accepted against moles of permanganate reduced. Three straight lines through the origin represent acidic, neutral, and strongly alkaline media. The slopes of these lines should be:

3. Formation of a complex can stabilise an unusual oxidation state of a transition metal because:

4. A set of radii for tripositive actinoid ions shows a gradual overall decrease as atomic number increases. The trend is identified as:

5. Match each ion in Column I with its -electron classification in Column II.

The appropriate matching is:

6. A mineral sample is found to contain naturally occurring members of the actinoid series. Which pair is most reasonably expected in such a sample?

7. When a transition-metal atom forms a positive ion, electrons are generally removed first from the:

8. Examine the oxidation-state information below.

The consistent rows are:

9. The ground-state configuration associated with scandium, the first member of the series, is:

10. Complete disproportionation of of according to

produces:

11. A learner says, “Because actinoid compounds show greater covalency, every actinoid compound must be a neutral molecular substance.” The best evaluation is:

12. After fusion and water extraction, sodium chromate can be separated from iron(III) oxide mainly because:

13. Complete conversion of of into chromate occurs according to

The amounts of consumed and formed are respectively:

14. A reaction is performed in a strongly alkaline solution, but the product equation is written with as the permanganate reduction product. The most likely diagnosis is:

15. An atom has the supplied configuration . Given that radon contains electrons, the atomic number of the atom is:

16. The molecular equation representing conversion of sodium chromate into sodium dichromate by sulphuric acid is:

17. Four tripositive ions have configurations , , , and . Arrange them by increasing number of unpaired electrons:

18. The sequence of highest oxidation states for , , , , and is:

19. A sample is represented by the average formula . The formula indicates that:

20. A sample of is used separately in acidic, neutral, and strongly alkaline reductions. The numbers of equivalents represented are respectively:

21. Match each species in Column I with its configuration in Column II.

The appropriate matching is:

22. Study the supplied first ionisation enthalpy data.

The most suitable interpretation is:

23. An actinoid atom forms a ion, but its radioactive behaviour remains. This observation shows that:

24. Acidified potassium permanganate is passed through a solution containing hydrogen sulphide. Which observation is most consistent with the redox reaction?

25. Match each aqueous ion in Column I with its commonly observed colour in Column II.

The appropriate matching is:

26. The general electronic configuration used for actinoid atoms is:

27. Two lanthanoid ions have configurations and . Assuming electrons occupy the seven orbitals according to Hund’s rule, their numbers of unpaired electrons are respectively:

28. A graph plots the ionic radius of on the vertical axis against increasing atomic number on the horizontal axis. The graph should show:

29. Between two tripositive lanthanoid ions, ion P is larger than ion Q. Their hydroxides are compared under similar conditions. Which prediction is most reasonable?

30. A learner proposes in place of the commonly used configuration for gadolinium. The best evaluation is:

31. A pale-green solution becomes yellow-brown after exposure to an oxidising agent. Analysis confirms that the metal is iron throughout. The most likely change is:

32. A student claims, “Because is common among actinoids, species such as and cannot exist.” The best evaluation is:

33. generally acts as a reducing species because it can be oxidised to:

34. Assertion: Silver is commonly written as .
Reason: A completely filled subshell can contribute to the stability of this electron distribution when the and energies are close.

35. An energy-profile graph shows the same reactant and product energy levels for two pathways. Path P has a high peak, while Path Q has a lower peak. If Q represents the catalysed pathway, the graph shows that the catalyst:

36. Oxidation of uranium from to , where uranium is , involves:

37. Consider the following statements about configuration irregularities in later transition series.
Statement I: They may arise because the and subshells are close in energy.
Statement II: Every irregularity can be predicted by applying one universal half-filled-subshell rule.
Statement III: Supplied configuration data should be used when a later-series ground state is requested.
Statement IV: An configuration is possible for a -block atom.
The valid statements are:

38. What mass of , with molar mass , is required to prepare of a solution?

39. Complete reaction of of with in acidic medium requires:

40. Two successive ions have the same charge, but the second has a slightly smaller radius. The most appropriate explanation is:

41. The oxidation state of chromium in and manganese in is respectively:

42. The valid correction to the impossible proposal for lutetium is:

43. A claim states, “Every ion of a transition element is paramagnetic.” The best correction is:

44. A metal ion has a configuration. The group number of M is:

45. A standardised potassium permanganate solution is stored for a long time in a dirty bottle containing traces of reducing material. Its concentration is most likely to:

46. The oxidation states of the transition metals in , , and are respectively:

47. For with molar mass , the equivalent masses in neutral medium and strongly alkaline medium are respectively:

48. Using , , and , the theoretical mass of obtainable from of pure is:

49. For oxidation of oxalate by acidified permanganate, the balanced ionic equation is:

50. The predominance of the oxidation state among lanthanoids should not be interpreted to mean that: