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NEET2022Chemistryd and f Block ElementsActual

Gadolinium has a low value of third ionisation enthalpy because of

Options

  1. Ahigh exchange enthalpy
  2. Bhigh electronegativity
  3. Chigh basic character
  4. Dsmall size

Correct answer

A. high exchange enthalpy

Step-by-step solution

Exchange energy is the energy released when two or more electrons with the same spin exchange their positions in the degenerate orbitals of a subshell. On losing third e - , Gadolinium achieves half filled 4 f -orbital configuration, which has higher exchange enthalpy. Gd = Xe   4 f 7 5 d 1 6 s 2 .

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