Question

The trivalent ion having largest size is

• A. Ti
• B. Zr
• C. Hf
• D. La

Answer 1

The correct option is D La

The most significant characteristic of Lanthanides is the contraction of the atomic size with increase in atomic number called lanthanide contraction. While moving along the lanthanides series from Ce(58) to Lu71, a regular decrease in the size of the atom/ion and increase in atomic number is observed. This decrease in size is called the lanthanide contraction. The decrease in size, though continuous, is not regular. Lanthanide contraction takes place due to imperfect shielding of one 4f- electron which increases by one more in the same sub-shell.
So due to this contraction La have highest radii.