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

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

2. Acidified potassium dichromate is added to an excess of potassium iodide solution. Which observation is most consistent with the reaction?

3. Consider the following statements about the chemical reactivity of lanthanoids.
Statement I: Lanthanoids are strongly electropositive and commonly form predominantly ionic compounds containing .
Statement II: Earlier lanthanoids are generally more reactive than later members, although the change across the series is gradual.
Statement III: Lanthanoids react with dilute non-oxidising acids to form salts and liberate hydrogen.
Statement IV: On heating, lanthanoids react with halogens to form trihalides, and many form -type oxides with oxygen.
The valid statements are:

4. During chromite fusion, the oxygen supply is severely restricted while the amounts of ore and sodium carbonate remain unchanged. The most likely result is:

5. A group- metal forms a high-spin ion. Its -electron count, number of unpaired electrons, and spin-only magnetic moment are:

6. A learner arranges actinoids by -electron count and concludes that radioactivity must increase regularly with each added electron. The best evaluation is:

7. 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.

8. Select the balanced reduction half-reaction for dichromate in acidic medium:

9. The statement that an oxidation state is “stable” means that the state:

10. A stainless-steel sample contains chromium and nickel by mass. Pure chromium is added until chromium forms of the new total mass. The mass of chromium added and the new nickel percentage are:

11. The reaction

demonstrates that behaves as:

12. Equal portions of acidified dichromate and permanganate solutions are separately reacted with excess . The amounts of oxidised by dichromate and permanganate are respectively:

13. The disproportionation of in water is encouraged in part because:

14. A group- metal ion has a configuration. Its oxidation state is:

15. A configuration model assumes that orbital filling is determined only by a rigid order and therefore predicts for chromium and for copper. The main weakness of this model is that it:

16. If two metals have similar atomisation and ionisation enthalpies, but has a much more exothermic hydration enthalpy than , the reduction potential is expected to be:

17. A transition metal X forms , , and . Experiments show that neutralises acids, reacts with both acids and alkalis, and forms an oxoacid with water. The observations are best explained by:

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

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

The amount of required to react completely with of is:

20. In the balanced preparation equation

the value of is:

21. Use the following stability description. State P is favoured in a strongly oxidising oxide lattice. State Q is favoured as a hydrated aqueous ion. State R is stabilised only after binding to a particular ligand. The most suitable conclusion is:

22. In the neutral-medium half-reaction

the value of is:

23. A student inserts fourteen additional positions into period after the element associated with group . These positions are intended to represent progressive filling of:

24. A graph plots spin-only magnetic moment against the number of unpaired electrons for to . The expected graph:

25. Using

and

the standard cell potential for

is:

26. In a ligand-rich medium, is stabilised strongly enough for the comproportionation

to proceed essentially to completion. If of copper metal is mixed with of , the total amount of copper formed in the oxidation state is:

27. The expected order of increasing acidic character is:

28. In aqueous solution, may undergo the reaction:

This reaction is classified as:

29. During the titration of an acidified solution with potassium permanganate, the end point is identified by:

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

31. During a titration of with acidified potassium dichromate, an external indicator is commonly required because:

32. A lanthanoid metal reacts with water according to:

A sample of the metal has molar mass . If hydrogen is obtained in yield, its volume at standard conditions, using , is:

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

34. The pair of ions having the same -electron count is:

35. When of undergoes complete disproportionation according to

the amounts of and formed are respectively:

36. A learner argues that one equivalent of dichromate must react with one mole of because the equivalent ratio is . The best correction is:

37. Which observation most clearly indicates that colour cannot be used alone to decide whether an element is a transition element?

38. 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:

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

40. Transition metals readily form alloys with one another mainly because many of them have:

41. The value of depends on the combined balance of:

42. A lanthanoid metal forms of the oxide . If the same mass of metal reacts completely with water according to

the molar mass of the metal and the amount of hydrogen formed are:

43. The formulas and characteristic colours of manganate and permanganate ions are respectively:

44. In the acidic reduction half-reaction

the values of and are respectively:

45. Using the spin-only relation

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

46. The high enthalpy of atomisation of many transition metals is primarily associated with:

47. Two supplied electronic configurations are and . Which conclusion about their compatibility with the actinoid pattern is most appropriate?

48. The colour of many transition-metal ions is primarily associated with:

49. Potassium dichromate is suitable for use as a primary standard mainly because it is:

50. The thermodynamic route used to analyse conversion of into is best represented by: