Question

Which one of the following is $d$ block element?

• A. Gd
• B. Hs
• C. Es
• D. Cs

Answer 1

Answer: (B)

Hs

Answer 2

The element in which last electron enters in $d$-orbital is called $d$-block element.
The electronic configuration of the given elements are as follows
$G d(64)=[X e] 6 s^{2}, 4 f^{7}, 5 d^{1}$
$H s(108)=[R n] 7 s^{2}, 5 f^{14}, 6 d^{6}$
$E s(99)=[R n] 7 s^{2}, 5 f^{11}$
$C s(55)=[X e] 6 s^{1}$
Thus, $Hs$ is a $d$-block element

So, the correct answer is (B): $Hs$