Chemistry - PERIODIC TABLE Question with Solution | TestHub

The lanthanide contraction causes the atomic radii of elements in the same group but different periods to deviate from expected trends.

A. $Sc<Y<La$: Correct. Radii generally increase down a group.

B. $Ti<Zr\approx Hf$: Correct. Lanthanide contraction makes Zr and Hf almost identical in size.

C. $Sc>Y>La$: Incorrect. Radii increase down a group, so $Sc<Y<La$.

D. $Sc<La>Y$: Incorrect. This order is illogical as La is below Y.

The incorrect order is $Sc>Y>La$.