The correct order of ionic radii of `Y^(3+), La^(3+), Eu^(3+)` and `Lu^(3+)` is :

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

Y is the first member of 4d-transition series. Its size is less than the size of the lanthanoids. In case of lanthanoids, the size decreases from `La^(3+) to Lu^(3+)`. Therefore, the correct order of ionic radii is
`Y^(3+) lt Lu^(3+) lt Eu^(3+) lt La^(3+)`