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

1. Assertion: The subshell is filled before in the simplest Aufbau description, yet electrons are removed before electrons during formation of first-row transition-metal cations.
Reason: The relative energies of and change after the subshells become occupied.

2. An atom has the supplied configuration . Given that xenon contains electrons, the atomic number and block classification of the atom are:

3. Assertion: A transition-metal ion may become coloured when surrounded by ligands.
Reason: The ligand environment can split the orbitals, allowing absorption of selected visible wavelengths through electronic transitions.

4. An ordinary laboratory solution of potassium permanganate is generally standardised before quantitative use because:

5. The set that represents the usual acidic reduction changes is:

6. Examine the medium-dependent behaviour of permanganate.

The consistent rows are:

7. A display material emits narrow, characteristic colours after excitation. A lanthanoid compound is selected because:

8. A laboratory requires an oxidant solution that can be prepared directly from an accurately weighed pure solid without first standardising the solution. The more suitable choice is:

9. 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:

10. Mechanical filling predicts for chromium and for copper. On converting both predictions to their observed configurations, the total number of electrons gained by the subshells and lost by the subshells across the two atoms is:

11. Copper and zinc both have completely filled subshells in their neutral atoms. The distinguishing configuration feature is:

12. The spin-only magnetic moment of a ion is closest to:

13. In a practical titration of acidified permanganate with oxalate, the reaction mixture is warmed initially because:

14. Some lanthanoid ions with complementary configurations and show related colours. The safest interpretation is:

15. A simple ion generally does not show an ordinary - absorption because:

16. Transition metals generally have high densities because they commonly possess:

17. A student compares , , and . The sound evaluation is:

18. An element is classified operationally as a transition element when it has:

19. A reducing agent X is oxidised according to the supplied half-reaction

If acidified permanganate is reduced to , the mole ratio of X to required for complete electron balance is:

20. Use the graph description below. The vertical axis represents melting point and the horizontal axis runs across a transition series. Curve P rises toward a broad central high region and then falls irregularly near the end. Curve Q decreases smoothly from the first element to the last. Curve R remains horizontal, while Curve S has its only maximum at the end. The most realistic curve is:

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

The appropriate matching is:

22. A newly produced actinoid isotope decays so rapidly that only tiny amounts can be studied soon after its formation. Which inference is most reasonable?

23. Examine the comparison between lanthanoids and actinoids.

The consistent rows are:

24. Three electrons are to be placed in five degenerate orbitals. The ground-state arrangement that follows Hund’s rule is:

25. Match the electronic situation in Column I with the description in Column II.

The appropriate matching is:

26. For one mole of permanganate, the order of decreasing oxidising capacity based on the number of electrons accepted is:

27. Pyrolusite, the manganese ore used in the preparation of potassium manganate, is mainly:

28. The positive standard reduction potential of the couple indicates that, under standard conditions:

29. During the conversion of into , each manganese atom:

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

31. Assertion: Transition elements near the middle of a series generally show a wider range of oxidation states than elements near either end.
Reason: Near the middle, a larger number of and electrons can participate in bonding without the subshell being initially empty or completely filled.

32. A statement claims, “The element with the greatest nuclear charge in a transition series must always have the greatest first ionisation enthalpy.” The best evaluation is:

33. A transition metal forms a stable pentafluoride, but the corresponding simple aqueous ion is not observed. The most suitable conclusion is:

34. A transition-metal species is paramagnetic when it contains:

35. The molar mass of is . Its equivalent mass when reduced to in acidic medium is:

36. The inner-transition series are associated primarily with progressive filling of the:

37. Use the arrangements described below.
Arrangement P consists of one chromium atom surrounded tetrahedrally by four oxygen atoms.
Arrangement Q consists of two chromium-centred tetrahedra sharing one oxygen atom.
The correct identification is:

38. When of undergoes complete disproportionation according to

the amounts of and formed are respectively:

39. The catalytic activity of many transition metals and their compounds is commonly linked to:

40. Chromium and manganese both contain a subshell in their neutral ground states. Their configurations differ because:

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

42. A process requires permanganate to be reduced without forming either dissolved or a solid precipitate. The most suitable condition and product are:

43. In the reaction between acidified permanganate and hydrogen sulphide:

44. In a charge-transfer transition, electron density is promoted mainly between:

45. Which comparison between lanthanoid contraction and actinoid contraction is most accurate?

46. Examine the simplified trend below.

The trend is best explained by:

47. Acidified permanganate is added to a solution containing . How do the oxidation states change?

48. An orange acidified dichromate solution becomes green after reaction with a reducing agent. The colour change indicates:

49. The principal reason electrons provide relatively weak shielding is that:

50. Suppose the nuclear charge increases across a transition series while the shielding effect of added electrons also becomes stronger. The most reasonable prediction is that atomic radius will: