Answer: Mercury (Hg).
- A Mercury (Hg)
- B Zinc
- C Iron
- D Nickel
Correct answer: A. Mercury (Hg)
Explanation: Mercury is the only metal that is liquid at room temperature; it freezes at -39°C.
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.