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

Answer

D

Explanation

On account of lanthanide contraction, we have the order `La^(3+) gt Eu^(3+) gt Lu^(3+)`
The correct order of ionic radii of given ions is actucally
`{:(Lu^(3+),lt,Y^(3+),lt,Eu^(3+),lt,La^(3+)),((0.861A^(@)),,(0.900),,(0.947),,(1.032A)^(@)):}`
`Y^(3+)` ion has lower ionic radius in comparison to `La^(3+)` because it lies immediately above it in the periodic table.