Question

Due to lanthanide contraction :

• A. $Fe,Co,Ni$ have equal size
• B. $Zr$ and $Hf$ have equal size
• C. all $f-$block ions have equal size
• D. all isoelectronic ions have equal size

Answer 1

Answer: (B)

$Zr$ and $Hf$ have equal size

The lanthanide contraction cancels almost exactly the normal size increase on descending a group of transition elements. Thus, $Zr$ and $Hf$ have equal size.