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STD 12 - 4. d and f- block elements — NEET STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceNEETSTD 12 - 4. d and f- block elements4 Marks
MCQ
Which one of the following statements concerning lanthanides elements is false
  • A
    Lanthanides are separated from one another by ion exchange methods
  • ✓
    The ionic radii of trivalent lanthanides steadily increase with increase in atomic number
  • C
    All lanthanides are highly dense metals
  • D
    Most typical oxidation of lanthanides is $ + 3$
✓

Answer

Correct option: B.
The ionic radii of trivalent lanthanides steadily increase with increase in atomic number
b
The chemistry of the lanthanides differs from main group elements and transition metals because of the nature of the 4 orbitals. These orbitals are "buried" inside the atom and are shielded from the atom's environment by the $4 d$ and $5 p$ electrons. As a consequence, the chemistry of the elements is largely determined by their size, which decreases gradually with increasing atomic number. This phenomenon is known as the lanthanide contraction. All the lanthanide elements exhibit the oxidation state $+3$.Because of this lanthanide contraction, all lanthanide metals are highly dense.

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