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NEETChemistryd and f Block Elements

Why is the lanthanoid contraction associated with the filling of 4f orbitals before 5d series of elements begin?

Options

  1. ABecause 4f orbitals have a higher shielding effect.
  2. BBecause 5d orbitals have a higher shielding effect.
  3. CBecause 4f orbitals have a lower shielding effect.
  4. DBecause 5d orbitals have a lower shielding effect.

Correct answer

C. Because 4f orbitals have a lower shielding effect.

Step-by-step solution

The lanthanoid contraction is associated with the filling of 4f orbitals before 5d series of elements begin, and this is because the shielding of one 4f electron by another is less effective.

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