NEET2010ChemistryStructure of AtomActual
Which of the following pairs has the same size?
Options
- AFe ²⁺, Ni ²⁺
- BZr ⁴⁺, Ti ⁴⁺
- CZr ⁴⁺, Hf ⁴⁺
- DZn ²⁺, Hf ⁴⁺
Correct answer
C. Zr ⁴⁺, Hf ⁴⁺
Step-by-step solution
In general, the atomic and ionic radii increases on moving down a group. But the elements of second transition series (eg, Zr , Nb , Mo etc) have the almost same radii as the elements of third transition series (eg, Hf, Ta, W etc). This is because of lanthanide contraction ie, imperfect shielding of one 4 f -electron by another.