Answer: (n-1)d 1-10 ns 0-2.
- A (n-1)d<sup>1-10</sup>ns<sup>0-2</sup>
- B ns<sup>1-2</sup>
- C (n-2)f<sup>1-14</sup>ns<sup>2</sup>
- D ns<sup>2</sup>np<sup>1-6</sup>
Correct answer: A. (n-1)d<sup>1-10</sup>ns<sup>0-2</sup>
Explanation: Transition elements progressively fill the (n-1)d orbitals with the ns orbital usually holding 1 or 2 electrons, giving (n-1)d<sup>1-10</sup>ns<sup>0-2</sup>.
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.