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

1. Examine the oxidation-state and configuration data below.

The consistent rows are:

2. A mixture contains only and . Chemical analysis shows that the mixture contains of copper. Using and , the amounts of and , respectively, are:

3. Assertion: The melting point must change smoothly from chromium to manganese to iron because the (3d)-electron count changes progressively across the sequence.
Reason: Transition-metal melting points depend on the complete metallic-bonding and structural situation, so an element such as manganese can deviate markedly from a smooth trend.

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

5. A laboratory worker must handle a solution containing chromium(VI). The safest procedure is to:

6. The geometry around manganese in both manganate and permanganate ions is approximately:

7. Two elements lie on opposite sides of manganese in the first transition series. Element X is an early member whose maximum oxidation state equals its group number, while element Y is a later member approaching a filled subshell. The more reasonable comparison is:

8. The -factor of when it is reduced to in acidic medium is:

9. A bar graph represents moles of electrons accepted per mole of oxidant under four conditions:
Case P: acidified
Case Q: neutral-medium
Case R: strongly alkaline
Case S: acidified
Arrange the bar heights in decreasing order:

10. An oxide of a transition metal reacts with both a strong acid and a strong alkali. The oxide should be classified as:

11. Assertion: is often relatively stable in aqueous chemistry.
Reason: has a half-filled configuration.

12. Comproportionation is a redox process in which:

13. Metal P has relative atomic mass and relative atomic volume , while metal Q has relative atomic mass and relative atomic volume . Metal R has relative atomic mass and the same relative density as Q. Using

the required relative atomic volume of R and the density order are:

14. As the oxidation state of a transition metal increases, the acid-base character of its oxides generally changes from:

15. Assertion: Lanthanoid contraction contributes both to the similarity of zirconium and hafnium and to the decrease in basicity from to .
Reason: Poor shielding by electrons causes the effective nuclear attraction to increase across the lanthanoid series.

16. Two tripositive ions have idealised configurations and . Which statement is most appropriate?

17. Compared with lanthanoid compounds in corresponding oxidation states, actinoid compounds generally show:

18. 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.

19. Examine the following statements.
Statement I: has a configuration.
Statement II: has a configuration.
Statement III: has a configuration.
The valid statements are:

20. Consider the following statements about the position of the -block.
Statement I: Lanthanoids are associated with period .
Statement II: Actinoids are associated with period .
Statement III: Their separate display prevents the main periodic table from becoming excessively wide.
Statement IV: Their detached position means they do not belong to any period.
The valid statements are:

21. Three hypothetical elements have the configurations shown below.

On the basis of the operational definition, the transition element is:

22. Across a transition series, the phrase “gradual filling of the subshell” does not imply that:

23. The statement “ is always smaller than every ion” is unreliable because:

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

25. Assertion: Exact actinoid configurations show greater irregularity than a simple stepwise -filling pattern suggests.
Reason: The , , and subshells are close in energy.

26. Using the spin-only relation

where is the number of unpaired electrons, the ratio is closest to:

27. A claim states, “Every metal in groups to is a transition element because all of them are metallic.” The most suitable evaluation is:

28. Assertion: The configurations and receive special attention in the lanthanoid series.
Reason: They represent half-filled and completely filled subshells, respectively, and have enhanced stability.

29. Use the periodic-table arrangement described below. A detached row associated with period is placed beneath the lanthanoid row, and its differentiating electrons enter an inner subshell. This row represents:

30. The colours of actinoid ions may arise from:

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

32. Chromium(VI) oxide reacts with hydroxide ions according to:

The amount of required to react completely with of is:

33. For an uncatalysed reaction, the forward and reverse activation energies are and , respectively. A transition-metal catalyst lowers the forward activation energy to . If the catalyst lowers both activation barriers by the same amount, the reaction enthalpy and the catalysed reverse activation energy are:

34. 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:

35. For a -orbital splitting energy , an increase in corresponds to absorption of light with:

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

37. A subshell has . Using the relations orbitals per subshell and a maximum of electrons per orbital, its orbital count and maximum electron capacity are:

38. A learner expects lanthanoid radii to increase because one electron is added at each successive element. The best evaluation is:

39. For ions of the same transition element in comparable coordination environments, increasing the positive oxidation state generally causes the ionic radius to:

40. During fusion of pyrolusite with excess potassium hydroxide, the oxygen supply is severely restricted. The most likely result is:

41. Potassium permanganate can act as a self-indicator in many acidic redox titrations because:

42. The oxidation half-reaction for oxalate ions is:

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

44. The energies of the and subshells in transition-metal atoms are described as relatively close. This closeness chiefly helps explain:

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

46. In strongly alkaline solution, one mole of accepts one mole of electrons. The principal manganese-containing product and its characteristic colour are:

47. A substitutional solid-solution alloy is produced when:

48. Nichrome is well suited for electrical heating elements because it combines:

49. An element is placed in the -block when its differentiating electron enters mainly the:

50. Match the configuration fragment in Column I with the most suitable interpretation in Column II.

The appropriate matching is: