The correct order of ionic radii `Y^(3+)` , `La^(3+)` , `Eu^(3+)` and `Lu^(3+)` is `(AT. No : Y = 39, La = 57, Eu = 63, Lu = 71)`

Options

A. `Y^(3+) lt La^(3+) lt Eu^(3+) lt Lu^(3+)`
B. `Y^(3+) lt Lu^(3+) lt Eu^(3+) lt La^(3+)`
C. `Lu^(3+) lt Eu^(3+) lt La^(3+) lt Y^(3+)`
D. `La^(3+) lt Eu^(3+) lt Lu^(3+) lt Y^(3+)`

Answer

B

Explanation

The correct order of ionic radii of `Y^(3+), La^(3+), Eu^(3+)`, and `Lu^(3+)` is `Y^(3+) lt Lu^(3+) lt Eu^(3+) lt La^(3+)` because `Eu` to `Lu` are members of lanthanide series so they show lanthanide contraction and `La` is the representative element of all elements of such series and `Y^(3+)` ion has lower radii as compared to `La^(3+)` because it lies immediately above it in the periodic table.