Answer: Fully filled d 10 is extra stable.
- A Fully filled d<sup>10</sup> is extra stable
- B It has odd atomic number under usual circumstances
- C 3d orbitals are empty according to most researchers
- D It is a noble gas in the majority of cases studied
Correct answer: A. Fully filled d<sup>10</sup> is extra stable
Explanation: A fully filled d<sup>10</sup> sub-shell has extra stability; Cu 'borrows' one electron from 4s to achieve [Ar]3d<sup>10</sup> 4s<sup>1</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.