NEET Chemistry: Transition Elements properties and complex formation 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: 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: 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: D — All electrons are paired.

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

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.

Correct answer: D — Linkage isomerism

Linkage isomerism occurs when the connectivity of the ligands changes, leading to different spatial arrangements of the same set of ligands, which is common in polydentate complex formation.

Correct answer: C — the total number of ligands attached

The coordination number is the number of ligand donor atoms directly bonded to the central metal ion.

Correct answer: B — d⁵

For d⁵ configuration (e.g., Mn²⁺), the pairing energy is relatively high compared to the crystal field splitting energy (Δₒ), resulting in the maximum number of unpaired electrons, thus favoring the high spin state. (d¹ is always low spin, d⁶ can be high or low spin depending on ligands, d¹⁰ is always low spin).

Correct answer: B — d orbitals

Transition elements (d-block) are defined by the fact that the last electron enters the d-orbital, meaning they possess partially filled d-orbitals in their valence shell.

Correct answer: C — Lanthanide contraction

The f-block elements (lanthanides and actinides) are characterized by the filling of the 4f and 5f orbitals, which leads to the unique properties associated with the lanthanide contraction.

Correct answer: B — The number of unpaired electrons

The magnetic moment (spin-only) is directly proportional to the number of unpaired electrons. The formula used is μ= √(n(n+2)) BM, where n is the number of unpaired electrons.