Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NEETChemistryd and f Block Elements

What is the reason for the regular decrease in atomic radii known as Lanthanoid contraction?

Options

  1. AThe filling of 4f before 5d orbital.
  2. BThe intervention of the 4f orbitals.
  3. CThe imperfect shielding of one electron by another in the same set of orbitals.
  4. DThe net electrostatic attraction between the nuclear charge and the outermost electron.

Correct answer

A. The filling of 4f before 5d orbital.

Step-by-step solution

Lanthanoid contraction is caused by the filling of 4f orbitals before 5d orbitals, resulting in a regular decrease in atomic radii.

Practice d and f Block Elements on Quantrex Academy →

More from d and f Block Elements

Although +3 oxidation state is most common in lanthanoids, cerium still shows +4 oxidation state because : 2026The lanthanide ion having four unpaired electrons is (Given : Atomic numbers of Ce =58 , Nd =60 , Tb =65 and Ho =67 ) 2026The green paramagnetic species formed by heating KMn O₄ at 513 K is 2026The calculated 'spin-only' magnetic moment of Ti ²⁺ (3d^2) is : 2026Match List I with List II : List I (Transition metal/compound/complex) List II (Catalytic Role) A. V ₂ O ₅ I. Preparation of ammonia from N ₂/ H ₂ mixture B. Fe II. Polymerisation 2026Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R . Assertion A : Generally, 3d transition metals have high melting points. Reas 2026Given below are two statements : Statement I : Ferromagnetism is considered as an extreme form of paramagnetism. Statement II : The number of unpaired electrons in a Cr ²⁺ ion ( Z 2025Which of the following set of ions act as oxidising agents? 2024 Full d and f Block Elements list All NEET PYQs