MCQ
Which of the following pairs has the same size ?
- A$Fe^{2+}, Ni^{2+}$
- B$Zr^{4+}, Ti^{4+}$
- ✓$Zr^{4+}, Hf^{4+}$
- D$Zn^{2+}, Hf^{4+}$
✓
Answer
Correct option: C.
$Zr^{4+}, Hf^{4+}$
c
In general, the atomic and ionic radii increases on moving down a group but the elements of second transition series $(Zr, Nb, Mo)$ have almost same radii as the elements of third transition series $(Hf, Ta, W, etc)$. This is because of lanthanoid contraction, i.e.
In general, the atomic and ionic radii increases on moving down a group but the elements of second transition series $(Zr, Nb, Mo)$ have almost same radii as the elements of third transition series $(Hf, Ta, W, etc)$. This is because of lanthanoid contraction, i.e.
imperfect shielding of one $4f \;e^{-}$ by another.
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