Question

Element with atomic number $81$, is present in which block?

• A. s-block
• B. p-block
• C. d-block
• D. f-block

Answer 1

Answer: (B)

The electronic configuration of the atom with atomic number $81$ is
$=[Xe]4f^{14},5d^{10},6s^2{p}^1$
Electronic configuration shows that $p$ orbitals of the element are incomplete, hence it belongs to $p$ block (III A group element, ie, Tl).