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🧪 Chemistry  ·  d- and f-Block Elements  ·  NEET & JEE

The number of unpaired d-electrons in the Mn2+ ion is:

Answer: 5.

  • A 5
  • B 4
  • C 3
  • D 2

Correct answer: A. 5

Explanation: Mn (Z = 25) is [Ar]3d54s2; Mn2+ is [Ar]3d5 with all five d-electrons unpaired, giving high paramagnetism.

Colours of Common Transition Metal Ions (Aqueous)Cu²⁺ blueFe²⁺ pale greenFe³⁺ brown-yellowMn²⁺ pale pinkNi²⁺/Cr³⁺ greenColour arises from d-d electron transitions - d⁰ ions like Sc³⁺, Ti⁴⁺ are colourless

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.

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