Question 1

Which of the following statements correctly describes the preparation of potassium dichromate ($K_2Cr_2O_7$)?

Accepted Answer

Correct Option: B. Solution: Potassium dichromate is prepared by treating sodium dichromate with potassium chloride.

Question 2

Which of the following factors contributes to the complexity of actinoid chemistry compared to lanthanoid chemistry?

Accepted Answer

Correct Option: A. Solution: The complexity of actinoid chemistry arises from the presence of multiple oxidation states, unlike the lanthanoids which predominantly exhibit a +3 oxidation state.

Question 3

Which of the following is a consequence of the lanthanoid contraction?

Accepted Answer

Correct Option: B. Solution: The lanthanoid contraction results in the radii of the third transition series elements being very similar to those of the corresponding members of the second series.

Question 4

Which of the following statements correctly differentiates between lanthanoids and actinoids?

Accepted Answer

Correct Option: A. Solution: Lanthanoids mainly show the +3 oxidation state with smoother trends, whereas actinoids exhibit a wider range of oxidation states and more complex chemistry.

Question 5

Why is the $E^\circ$ value for the $Mn^{3+}/Mn^{2+}$ couple more positive than that for $Cr^{3+}/Cr^{2+}$ or $Fe^{3+}/Fe^{2+}$?

Accepted Answer

Correct Option: A. Solution: The $E^\circ$ value for the $Mn^{3+}/Mn^{2+}$ couple is more positive because the third ionization energy of $Mn$ is significantly larger, making the +3 state less stable.

Question 6

Which of the following transition elements has an electronic configuration that deviates from the expected $(n-1)d^{10}ns^2$ pattern due to the stability of half-filled or fully-filled orbitals?

Accepted Answer

Correct Option: A. Solution: Copper ($Cu$) has an electronic configuration of $3d^{10}4s^1$, which deviates from the expected $3d^9 4s^2$ due to the stability of the fully-filled $3d$ subshell.

Question 7

Which factor primarily determines the color of transition metal ions in solution?

Accepted Answer

Correct Option: C. Solution: The color of transition metal ions in solution is primarily determined by the nature of the ligands, which affects the d-d transitions.

Question 8

Why do transition metals generally exhibit a decrease in atomic and ionic radii across a series?

Accepted Answer

Correct Option: A. Solution: As we move across a transition series, the nuclear charge increases, but the d electrons do not shield the outer electrons effectively, leading to a decrease in atomic and ionic radii.

Question 9

Why does the $E^\circ$ value for the $Cu^{2+}/Cu$ couple have a positive value?

Accepted Answer

Correct Option: A. Solution: The $E^\circ$ value for the $Cu^{2+}/Cu$ couple is positive because the high atomisation and ionisation enthalpies are not compensated by the hydration enthalpy.

Question 10

Which of the following oxides is acidic in nature?

Accepted Answer

Correct Option: B. Solution: $V_2O_5$ is an acidic oxide as it is a higher oxide of vanadium, which is generally acidic.

Question 11

Which of the following properties of transition metals is primarily due to the presence of unpaired d electrons and the resulting strong metallic bonding?

Accepted Answer

Correct Option: C. Solution: The high enthalpy of atomisation in transition metals is due to the strong metallic bonding involving unpaired d electrons, which allows for strong interatomic interactions.

Question 12

Which of the following statements correctly describes the position of f-block elements in the periodic table?

Accepted Answer

Correct Option: B. Solution: The f-block elements are placed at the bottom of the periodic table in a separate panel, involving the progressive filling of 4f and 5f orbitals.

Question 13

Which of the following complexes is known to stabilize unusual oxidation states of transition metals?

Accepted Answer

Correct Option: A. Solution: $[Fe(CN)_6]^{3-}$ is known to stabilize the iron in the +3 oxidation state, which is less common than the +2 state.

Question 14

Which of the following actinoid elements is known to exhibit the highest oxidation state in its compounds?

Accepted Answer

Correct Option: C. Solution: Neptunium ($Np$) can exhibit an oxidation state of +7, which is the highest among the actinoids.

Question 15

Which of the following statements correctly explains why $Zn$, $Cd$, and $Hg$ are not considered true transition metals?

Accepted Answer

Correct Option: A. Solution: According to IUPAC, transition metals are defined as metals having incomplete $d$ subshell in their atoms or common ions. $Zn$, $Cd$, and $Hg$ have a completely filled $d^{10}$ configuration in both their ground state and common oxidation states, thus they are not considered true transition metals.

Question 16

Which of the following properties is NOT typically associated with transition metals?

Accepted Answer

Correct Option: B. Solution: Transition metals are known for their high enthalpy of atomisation due to strong metallic bonding.

Question 17

Which of the following ions is stabilized by the formation of oxoanions?

Accepted Answer

Correct Option: C. Solution: $MnO_4^-$ is a stable oxoanion of manganese in its highest oxidation state, +7, which is stabilized by oxygen.

Question 18

In the context of transition metals, what is the significance of the lanthanoid contraction?

Accepted Answer

Correct Option: A. Solution: The lanthanoid contraction results in the radii of the third transition series being very similar to those of the second series, leading to similar chemical properties.

Question 19

The lanthanoid contraction is responsible for which of the following phenomena?

Accepted Answer

Correct Option: A. Solution: The lanthanoid contraction refers to the gradual decrease in ionic radii across the lanthanoid series, which is due to poor shielding by 4f electrons.

Question 20

Which of the following oxidation states is most commonly observed in actinoids?

Accepted Answer

Correct Option: B. Solution: The +3 oxidation state is most commonly observed in actinoids, similar to lanthanoids.

Question 21

Which transition metal ion is known for its exceptional stability in the +3 oxidation state due to its $d^5$ configuration?

Accepted Answer

Correct Option: B. Solution: $Fe^{3+}$ is known for its exceptional stability in the +3 oxidation state due to its $d^5$ configuration, which is stabilized by exchange energy.

Question 22

In the context of transition metals, what is the primary cause of paramagnetism?

Accepted Answer

Correct Option: B. Solution: Paramagnetism arises due to the presence of unpaired electrons, which have a magnetic moment associated with their spin.

Question 23

In the manufacture of sulphuric acid, which compound serves as a catalyst?

Accepted Answer

Correct Option: B. Solution: $V_2O_5$ is used as a catalyst in the contact process for the manufacture of sulphuric acid.

Question 24

Which of the following transition metals is known for having a stable +2 oxidation state due to its half-filled $d^5$ configuration?

Accepted Answer

Correct Option: A. Solution: Manganese ($Mn$) has a stable +2 oxidation state due to its half-filled $d^5$ configuration, which provides extra stability.

Question 25

Which of the following complexes is an example of a transition metal complex with a negative charge?

Accepted Answer

Correct Option: A. Solution: $[Fe(CN)_6]^{3-}$ is a complex ion with a negative charge, as indicated by the $3-$ charge.

Question 26

Which of the following ions is expected to be colorless due to its electronic configuration?

Accepted Answer

Correct Option: A. Solution: $Sc^{3+}$ has a $3d^0$ electronic configuration, which means there are no d-d transitions possible, making it colorless.

Question 27

Which factor is primarily responsible for the lanthanoid contraction observed in the series from lanthanum ($La$) to lutetium ($Lu$)?

Accepted Answer

Correct Option: A. Solution: The lanthanoid contraction is primarily due to the increasing nuclear charge with poor shielding by $4f$ electrons, leading to a decrease in atomic and ionic radii across the series.

Question 28

Why is the standard electrode potential $E^\circ$ for the $Cu^{2+}/Cu$ couple positive?

Accepted Answer

Correct Option: B. Solution: The $E^\circ$ for $Cu^{2+}/Cu$ is positive due to the high atomisation and ionisation enthalpies of copper, which are not sufficiently compensated by hydration enthalpy.

Question 29

Which of the following ions is colourless due to its electronic configuration?

Accepted Answer

Correct Option: A. Solution: $Sc^{3+}$ has a $3d^0$ configuration, which means there are no d-d transitions possible, making it colourless.

Question 30

What is the primary reason for the difficulty in achieving higher oxidation states for $Ni$, $Cu$, and $Zn$?

Accepted Answer

Correct Option: A. Solution: The difficulty in achieving higher oxidation states for $Ni$, $Cu$, and $Zn$ is primarily due to the complete filling of $d$ orbitals, leading to stable $d^{10}$ configurations.

Question 31

Which of the following transition metal ions is expected to have the highest spin-only magnetic moment?

Accepted Answer

Correct Option: B. Solution: $Mn^{2+}$ has 5 unpaired electrons, resulting in the highest spin-only magnetic moment calculated using the formula $\mu = \sqrt{n(n+2)}$, where $n$ is the number of unpaired electrons.

Question 32

Which of the following oxidation states is most commonly exhibited by lanthanoids?

Accepted Answer

Correct Option: B. Solution: The principal oxidation state of lanthanoids is +3, although +2 and +4 can also occur in some cases.

Question 33

Which of the following is a consequence of the lanthanoid contraction on the periodic table?

Accepted Answer

Correct Option: B. Solution: The lanthanoid contraction causes zirconium and hafnium to have very similar radii, leading to similar chemical properties and making them difficult to separate.

Question 34

Which of the following statements is true regarding the oxidation states of actinoids?

Accepted Answer

Correct Option: B. Solution: Actinoids exhibit a wider range of oxidation states due to the comparable energies of the 5f, 6d, and 7s levels.

Question 35

What is the primary reason for the high oxidation states of transition metals being stabilized by oxygen?

Accepted Answer

Correct Option: B. Solution: Oxygen stabilizes high oxidation states of transition metals due to its ability to form multiple bonds, which provides additional stability to the metal oxides.

Question 36

Which of the following transition metal compounds is used as a catalyst in the Haber process for ammonia synthesis?

Accepted Answer

Correct Option: C. Solution: Iron ($Fe$) is used as a catalyst in the Haber process for the synthesis of ammonia. The catalytic activity of iron is due to its ability to adopt multiple oxidation states and form complexes, which facilitates the conversion of nitrogen and hydrogen into ammonia.

Question 37

Why is the lanthanoid contraction significant in the chemistry of the third transition series?

Accepted Answer

Correct Option: B. Solution: The lanthanoid contraction causes the radii of the third transition series to be very similar to those of the second series, affecting their chemical properties.

Question 38

Which of the following statements correctly describes the difference between lanthanoids and actinoids in terms of their electronic configurations?

Accepted Answer

Correct Option: A. Solution: Lanthanoids have 4f orbitals progressively filled, while actinoids have 5f orbitals progressively filled, which is a key distinction in their electronic configurations.

Question 39

Which transition metal ion is most likely to be colorless in aqueous solution due to the absence of unpaired electrons?

Accepted Answer

Correct Option: A. Solution: Sc$^{3+}$ has an electronic configuration of $3d^0$, meaning it has no unpaired electrons, resulting in a colorless solution.

Question 40

Why do actinoids exhibit a greater range of oxidation states compared to lanthanoids?

Accepted Answer

Correct Option: A. Solution: The greater range of oxidation states in actinoids is attributed to the comparable energies of the 5f, 6d, and 7s levels.

Question 41

Which lanthanoid ion is known to be a strong reducing agent due to its electronic configuration?

Accepted Answer

Correct Option: A. Solution: Europium ($Eu^{2+}$) is a strong reducing agent because its $f^7$ configuration is stable, and it tends to revert to the more common +3 state.

Question 42

Why is the ionization enthalpy of $Fe^{3+}$ lower than that of $Mn^{2+}$ despite both having a $d^5$ configuration?

Accepted Answer

Correct Option: B. Solution: $Fe^{3+}$ has a $d^5$ configuration, which is stabilized by exchange energy, making its ionization enthalpy lower compared to $Mn^{2+}$.

Question 43

Why do transition metals generally have high melting points?

Accepted Answer

Correct Option: A. Solution: The high melting points of transition metals are attributed to the strong metallic bonding involving ns and (n-1)d electrons.

Question 44

Which of the following elements is not considered a transition metal despite being in the d-block?

Accepted Answer

Correct Option: B. Solution: Zinc is not considered a transition metal because it has a full $d^{10}$ configuration in its ground state as well as in its common oxidation states.

Question 45

Which transition metal ion is known for its strong oxidising property due to its half-filled $d^5$ configuration?

Accepted Answer

Correct Option: C. Solution: Iron in the $Fe^{3+}$ state has a $d^5$ configuration, which is stable and contributes to its strong oxidising properties.

Question 46

Which transition metal exhibits the highest number of oxidation states, and why?

Accepted Answer

Correct Option: A. Solution: Manganese ($Mn$) exhibits the highest number of oxidation states, ranging from +2 to +7, due to its ability to stabilize various oxidation states with its half-filled $d$ subshell.

Question 47

Which of the following transition metals is used as a catalyst in the Haber process?

Accepted Answer

Correct Option: B. Solution: Iron ($Fe$) is used as a catalyst in the Haber process for the synthesis of ammonia.

Question 48

Which of the following species is oxidized by acidified potassium dichromate ($K_2Cr_2O_7$)?

Accepted Answer

Correct Option: A. Solution: Acidified potassium dichromate is a strong oxidizing agent and can oxidize iodide ions ($I^-$) to iodine ($I_2$).

Question 49

What is the primary reason transition metals form complex compounds?

Accepted Answer

Correct Option: B. Solution: Transition metals form complex compounds due to their high ionic charges and the availability of d orbitals for bonding.

Question 50

In acidic solutions, potassium dichromate ($K_2Cr_2O_7$) can oxidize which of the following ions to its higher oxidation state?

Accepted Answer

Correct Option: D. Solution: In acidic solutions, $K_2Cr_2O_7$ can oxidize iodide ions to iodine, sulfide ions to sulfur, and tin(II) ions to tin(IV).

Question 51

Which of the following transition metal ions is expected to have the highest magnetic moment based on its electronic configuration?

Accepted Answer

Correct Option: B. Solution: The magnetic moment is calculated using the formula $\mu = \sqrt{n(n+2)}$, where $n$ is the number of unpaired electrons. Mn$^{2+}$ has 5 unpaired electrons, giving it the highest magnetic moment among the options.

Question 52

In the series from Scandium ($Sc$) to Zinc ($Zn$), which element has the lowest enthalpy of atomisation?

Accepted Answer

Correct Option: C. Solution: Zinc ($Zn$) has the lowest enthalpy of atomisation in the series, which is 126 kJ mol⁻¹.

Question 53

Which of the following lanthanoids exhibits a +4 oxidation state in its compounds, particularly in oxides?

Accepted Answer

Correct Option: A. Solution: Cerium ($Ce$) exhibits a +4 oxidation state, especially in its oxide $CeO_2$, due to the stability of its noble gas configuration.

Question 54

Which transition metal ion exhibits a pink color in aqueous solution?

Accepted Answer

Correct Option: B. Solution: $Mn^{2+}$ ions in aqueous solution exhibit a pink color due to their $3d^5$ electronic configuration.

Question 55

Which of the following statements best explains the similarity in atomic radii between 4d and 5d transition metals, such as Zr and Hf?

Accepted Answer

Correct Option: A. Solution: The lanthanoid contraction, which occurs due to poor shielding by 4f electrons, results in a smaller than expected increase in atomic size from 4d to 5d series, making elements like Zr and Hf have similar atomic radii.

Question 56

What is the primary reason for the catalytic activity of transition metals?

Accepted Answer

Correct Option: B. Solution: The catalytic activity of transition metals is primarily due to their ability to adopt multiple oxidation states and form complexes.

Question 57

Why is $[Cu(NH_3)_4]^{2+}$ considered a stable complex?

Accepted Answer

Correct Option: A. Solution: $[Cu(NH_3)_4]^{2+}$ is stable because copper has a strong affinity for ammonia, which acts as a ligand, stabilizing the copper in the +2 oxidation state.

Question 58

Which of the following transition metals is not considered a transition metal based on its electronic configuration?

Accepted Answer

Correct Option: B. Solution: Zinc has a completely filled $d^{10}$ configuration in its ground state as well as in its common oxidation states, hence it is not regarded as a transition metal.

Question 59

A transition metal complex exhibits a magnetic moment of 4.9 BM. Which ion is most likely to correspond to this measurement?

Accepted Answer

Correct Option: A. Solution: Cr$^{2+}$ with a $3d^4$ configuration has 4 unpaired electrons, leading to a magnetic moment of approximately 4.9 BM, which matches the given measurement.

Question 60

In an aqueous solution, which ion would you expect to exhibit a blue colour due to d-d transitions?

Accepted Answer

Correct Option: C. Solution: $Cu^{2+}$ has a $3d^9$ configuration, which allows d-d transitions that absorb light in the visible region, resulting in a blue colour.

Question 61

Which of the following statements correctly explains why transition metals form complex compounds?

Accepted Answer

Correct Option: B. Solution: Transition metals form complex compounds due to their small ionic sizes, high ionic charges, and availability of d orbitals for bonding.

Question 62

Why is it difficult for nickel ($Ni$) to achieve oxidation states higher than +2?

Accepted Answer

Correct Option: B. Solution: The high ionization enthalpy required to remove more electrons makes it difficult for nickel to achieve oxidation states higher than +2.

Question 63

Which of the following statements correctly describes the structural difference between chromate and dichromate ions?

Accepted Answer

Correct Option: A. Solution: The chromate ion ($CrO_4^{2-}$) is tetrahedral, while the dichromate ion ($Cr_2O_7^{2-}$) consists of two tetrahedra sharing one corner with a $Cr-O-Cr$ bond angle of 126°.

Question 64

In the reaction catalyzed by iron(III) ions involving iodide and persulphate ions, what is the role of iron(III) ions?

Accepted Answer

Correct Option: C. Solution: Iron(III) ions act as a catalyst in the reaction between iodide and persulphate ions, facilitating the reaction without being consumed.

The d- and f-Block Elemen..

Learning Objectives

Revision Notes & Summary

Notes on d- and f- Block Elements

1. Introduction to Transition Elements

2. Electronic Configurations

3. Oxidation States

4. Properties of Transition Metals

5. Inner Transition Elements

6. Preparation of Compounds

7. Reactions Involving Potassium Permanganate

8. Disproportionation Reactions

9. Stability of Oxidation States

10. Characteristics of Lanthanoids vs. Actinoids

11. Summary of Key Points

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Tips for Success

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Multiple Choice Questions

Q1.Which of the following statements correctly describes the preparation of potassium dichromate (K2Cr2O7K_2Cr_2O_7K2​Cr2​O7​)?

Correct Answer: B

Q2.Which of the following factors contributes to the complexity of actinoid chemistry compared to lanthanoid chemistry?

Correct Answer: A

Q3.Which of the following is a consequence of the lanthanoid contraction?

Correct Answer: B

Q4.Which of the following statements correctly differentiates between lanthanoids and actinoids?

Correct Answer: A

Q5.Why is the E∘E^\circE∘ value for the Mn3+/Mn2+Mn^{3+}/Mn^{2+}Mn3+/Mn2+ couple more positive than that for Cr3+/Cr2+Cr^{3+}/Cr^{2+}Cr3+/Cr2+ or Fe3+/Fe2+Fe^{3+}/Fe^{2+}Fe3+/Fe2+?

Correct Answer: A

Q6.Which of the following transition elements has an electronic configuration that deviates from the expected (n−1)d10ns2(n-1)d^{10}ns^2(n−1)d10ns2 pattern due to the stability of half-filled or fully-filled orbitals?

Correct Answer: A

Q7.Which factor primarily determines the color of transition metal ions in solution?

Correct Answer: C

Q8.Why do transition metals generally exhibit a decrease in atomic and ionic radii across a series?

Correct Answer: A

Q9.Why does the E∘E^\circE∘ value for the Cu2+/CuCu^{2+}/CuCu2+/Cu couple have a positive value?

Correct Answer: A

Q10.Which of the following oxides is acidic in nature?

Correct Answer: B

Q11.Which of the following properties of transition metals is primarily due to the presence of unpaired d electrons and the resulting strong metallic bonding?

Correct Answer: C

Q12.Which of the following statements correctly describes the position of f-block elements in the periodic table?

Correct Answer: B

Q13.Which of the following complexes is known to stabilize unusual oxidation states of transition metals?

Correct Answer: A

Q14.Which of the following actinoid elements is known to exhibit the highest oxidation state in its compounds?

Correct Answer: C

Q15.Which of the following statements correctly explains why ZnZnZn, CdCdCd, and HgHgHg are not considered true transition metals?

Correct Answer: A

Q16.Which of the following properties is NOT typically associated with transition metals?

Correct Answer: B

Q17.Which of the following ions is stabilized by the formation of oxoanions?

Correct Answer: C

Q18.In the context of transition metals, what is the significance of the lanthanoid contraction?

Correct Answer: A

Q19.The lanthanoid contraction is responsible for which of the following phenomena?

Correct Answer: A

Q20.Which of the following oxidation states is most commonly observed in actinoids?

Correct Answer: B

Q21.Which transition metal ion is known for its exceptional stability in the +3 oxidation state due to its d5d^5d5 configuration?

Correct Answer: B

Q22.In the context of transition metals, what is the primary cause of paramagnetism?

Correct Answer: B

Q23.In the manufacture of sulphuric acid, which compound serves as a catalyst?

Correct Answer: B

Q24.Which of the following transition metals is known for having a stable +2 oxidation state due to its half-filled d5d^5d5 configuration?

Correct Answer: A

Q25.Which of the following complexes is an example of a transition metal complex with a negative charge?

Correct Answer: A

Q26.Which of the following ions is expected to be colorless due to its electronic configuration?

Correct Answer: A

Q27.Which factor is primarily responsible for the lanthanoid contraction observed in the series from lanthanum (LaLaLa) to lutetium (LuLuLu)?