Question

The second element in third transitional series is:

• A. $Ac$
• B. $Ce$
• C. $Hf$
• D. $La$

Answer 1

The correct option is C $Hf$

d-block elements (transition elements) are divided into 4 series as following:
1) $3d$ series-Scandium to Zinc
2) $4d$ series- Yttrium to Cadmium
3) $5d$ series- Lanthanum to Mercury
4) $6d$ series- Actinium to Uub
Third transitional series is the $5d$ series. In $5d$ series, second element is $Hf$.