The dand fblock elements - Result Question 79

####79. The correct order of ionic radii of Y3+,La3+,Eu3+ and Lu3+ is

[2003]

(a) La3+<Eu3+<Lu3+<Y3+

(b) Y3+<La3+<Eu3+<Lu3+

(c) Y3+<Lu3+<Eu3+<La3+

(d) Lu3+<Eu3+<La3+<Y3+

(Atomic nos. Y=39,La=57,Eu=63,Lu=71 )

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Solution:

  1. (c) In lanthanide series there is a regular decrease in the atomic as well as ionic radii of trivalent ions (M3+) as the atomic number increases. Although the atomic radii do show some irregularities but ionic radii decreases from La(103pm) to Lu(86pm).


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