Answer: +3.
- A +2
- B +6
- C +4
- D +3
Correct answer: D. +3
Explanation: Lanthanoids almost always show the +3 state; +2 and +4 occur only for a few elements where they give stable f<sup>0</sup>, f<sup>7</sup> or f<sup>14</sup> configurations.
Aqueous solutions of transition metal ions show characteristic colours caused by electrons absorbing visible light to jump between split d-orbitals; the exact colour depends on the metal, its oxidation state, and surrounding ligands.
Concept context
Transition metals (d-block) and lanthanides/actinides (f-block). Known for coloured compounds, variable oxidation states, complex formation, and catalytic properties. Frequently tested in JEE and NEET.