Answer: Rare earth metals.
- A Rare earth metals
- B Alkaline earth metals
- C Transition metals
- D Noble metals
Correct answer: A. Rare earth metals
Explanation: Lanthanides (La-Lu) are also known as rare earth metals, though most are not actually rare.
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.