NEET Chemistry: d- and f-Block Elements Practice Questions

Correct answer: B — Fe3+

Transition metals, especially those with partially filled d-orbitals (like Fe3+), exhibit strong spin-orbit coupling which influences their magnetic and spectroscopic properties.

Correct answer: C — ns²

Lanthanides are characterized by the filling of the 4f orbitals, following the general configuration of the preceding elements (ns²).

Correct answer: D — f-block

The Lanthanides and Actinides are the elements filling the f-orbitals, which correspond to the f-block of the periodic table.

Correct answer: B — The participation of d-orbitals is crucial for forming both sigma (σ) and pi (π) bonds with ligands.

Transition elements exhibit complex bonding where the d-orbitals are partially filled and participate actively in the formation of both sigma (σ) and pi (π) bonds with ligands.

Correct answer: B — f-block elements

The lanthanoid contraction is the gradual decrease in atomic radii observed across the lanthanoid series (f-block elements) due to poor shielding by the filling 4f orbitals.

Correct answer: D — Manganese(II) ion

The Manganese(II) ion (Mn²⁺) is often considered the most stable configuration among the common oxidation states of transition metals, often correlating with the half-filled stability of the d-subshell.

Correct answer: A — Increased ionic radii

The lanthanide contraction causes a steady decrease in the atomic and ionic radii of the elements as we move across the series due to poor shielding by 4f electrons.

Correct answer: D — 6

The d-orbital has 5 degenerate orbitals (d₍xy), d₍xz), d₍yz), d₍x²-y²), d₍z²)), and each orbital can accommodate 2 electrons, thus providing a total of 5 × 2 = 10 electrons, which corresponds to 5 lone pairs (or 10 electrons).

Correct answer: C — Increases across the series

Due to poor shielding effect of the inner electrons, the atomic radius increases steadily from La to Lu (Lanthanide contraction is a related effect).

Correct answer: C — Uranium

Uranium (U) is the most well-known and commonly studied radioactive element among the Actinoids.

Correct answer: D — All electrons are paired.

Diamagnetism occurs when all electrons in the complex are paired, meaning there are no net unpaired electrons.

Correct answer: A — The magnetic properties are generally complex and depend on the specific element

The magnetic behavior of lanthanoids is complex, often exhibiting both paramagnetic and diamagnetic properties depending on the specific ion and crystal field environment.

Correct answer: A — Atomic radius

Lanthanoid contraction causes a steady decrease in the atomic radii of the elements as the atomic number increases, especially noticeable in the lanthanide series.

Correct answer: C — Cobalt (Co)

Cobalt (Co) and Iron (Fe) are common transition metals that readily form octahedral complexes (coordination number 6). While the specific preference depends on the ligand, Co(III) and Fe(III) complexes are well-known examples of octahedral coordination.

Correct answer: A — They form a mixture of ionic and covalent bonds

Transition metals exhibit variable bonding character; they form ionic bonds when bonding with highly electronegative elements and covalent bonds when bonding with less electronegative elements, leading to a mixture of both.