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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
Identify the incorrect statement among the following
  • A
    Lanthanoid contraction is the accumulation of successive shrinkages.
  • ✓
    As a result of lanthanoid contraction, the properties of $4d$ series of the transition elements have no similarities with the $5d$ series of elements.
  • C
    Shielding power of $4f$ electrons is quite weak.
  • D
    There is a decrease in the radii of the atoms or ions as one proceeds from $La$ to $Lu.$
✓

Answer

Correct option: B.
As a result of lanthanoid contraction, the properties of $4d$ series of the transition elements have no similarities with the $5d$ series of elements.
b
The regular decrease in the radil of lanthanide ions from $L a^{3+}$ to $L u^{3+}$ is known as lanthanides contraction. It is due to the greater effect of the increased nuclear charge than that of screening effect (shielding effect). As a result of lanthanide contraction, the atomic radii of element of $4 \mathrm{d}$ and $5 \mathrm{d}$ come closetr, so the properties of $4 \mathrm{d}$ and $5 \mathrm{d}$ -transition element shows the similarities

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