d- and f-Block Elements: NEET PYQ, 2018–2026

Q1 · Chemistry · d- and f-Block Elements

Which of the following first-row transition metals shows the greatest number of oxidation states?

• ASc
• BMn
• CZn
• DCu

Q2 · Chemistry · d- and f-Block Elements

In the laboratory preparation of KMnO₄, green K₂MnO₄ in alkaline solution is oxidised electrolytically at the anode to purple permanganate. What charge is needed to convert 0.10 mol of manganate completely to permanganate at 100% current efficiency? (F = 96500 C mol⁻¹)

• A9650 C
• B19300 C
• C28950 C
• D96500 C

Q3 · Chemistry · d- and f-Block Elements

Manganese reaches its group oxidation state of +7 in Mn₂O₇ and in MnO₄⁻. With fluorine, however, the highest binary fluoride of manganese is MnF₄. Which statement gives the correct reason for this difference?

• AOxygen can form multiple (pπ–dπ) bonds with the metal, whereas fluorine can only form single bonds, so oxygen stabilises higher oxidation states better
• BOxygen is more electronegative than fluorine and therefore removes more electrons from manganese
• CFluorine is a weaker oxidising agent than oxygen, so it cannot oxidise manganese beyond +4
• DThe second ionisation enthalpy of manganese is much higher than the third, so oxidation beyond +4 can occur only with oxygen

Q4 · Chemistry · d- and f-Block Elements

In acidic medium, how many electrons are accepted by one dichromate ion, Cr₂O₇²⁻, when it is reduced completely to Cr³⁺ ions?

• A2
• B3
• C6
• D12

Q5 · Chemistry · d- and f-Block Elements

Which of the following statements about the chemical behaviour of the actinoid metals is correct?

• AActinoids dissolve readily in aqueous NaOH with the liberation of dihydrogen.
• BConcentrated HNO₃ attacks actinoids more vigorously than HCl does.
• CActinoids are unreactive towards non-metals unless heated above red heat.
• DFinely divided actinoids are highly reactive and give a mixture of oxide and hydride with boiling water.

Q6 · Chemistry · d- and f-Block Elements

Lanthanoid ions tend to adopt a stable 4f⁷ (half-filled) configuration where possible. Atomic numbers: Ce = 58, Sm = 62, Eu = 63, Gd = 64, Tb = 65. Atomic ground-state configurations: Sm 4f⁶6s², Eu 4f⁷6s², Gd 4f⁷5d¹6s², Tb 4f⁹6s². Which set contains ions that ALL have the 4f⁷ configuration?

• AEu²⁺, Gd³⁺, Tb³⁺
• BEu²⁺, Gd³⁺, Tb⁴⁺
• CSm³⁺, Eu²⁺, Gd³⁺
• DEu³⁺, Gd³⁺, Tb³⁺

Q7 · Chemistry · d- and f-Block Elements

Transition metals of the first series readily form alloys with one another. The main reason is that the atoms of these metals have:

• AVery similar atomic radii, so an atom of one metal can replace an atom of another in the crystal lattice
• BThe same number of valence electrons, so their bonds are identical in every compound
• CThe same magnetic moment, so they align in one direction
• DIdentical densities, so they settle evenly when melted

Q8 · Chemistry · d- and f-Block Elements

The equivalent mass of KMnO₄ (molar mass 158 g mol⁻¹) depends on the medium in which it acts as an oxidant. What are its equivalent masses in strongly acidic solution (MnO₄⁻ → Mn²⁺) and in neutral solution (MnO₄⁻ → MnO₂), respectively?

• A31.6 and 52.7
• B52.7 and 31.6
• C31.6 and 158
• D31.6 and 79.0

Q9 · Chemistry · d- and f-Block Elements

Many Ln³⁺ ions are coloured in aqueous solution because of f–f transitions, and ions whose 4f configurations have the same number of unpaired electrons have similar colours. Atomic numbers: Pr = 59, Nd = 60, Sm = 62, Eu = 63, Gd = 64, Tb = 65, Ho = 67, Tm = 69. Which pair of Ln³⁺ ions is expected to have similar colours?

• APr³⁺ and Tm³⁺
• BNd³⁺ and Ho³⁺
• CSm³⁺ and Eu³⁺
• DGd³⁺ and Tb³⁺

Q10 · Chemistry · d- and f-Block Elements

On strong heating, potassium permanganate decomposes as 2KMnO₄ → K₂MnO₄ + MnO₂ + O₂. What volume of oxygen, measured at STP, is given by 31.6 g of KMnO₄? (Molar mass of KMnO₄ = 158 g mol⁻¹; molar volume at STP = 22.4 L mol⁻¹)

• A4.48 L
• B8.96 L
• C22.4 L
• D2.24 L