Question

An element $X$ belongs to fourth period and fifteenth group of the periodic table. Which of the following statements is true?

• A. It has a completely filled s-orbital and a partially filled d-orbital.
• B. It has completely filled s-and p-orbitals and a partially filled d-orbital.
• C. It has completely filled s-and p-orbitals and a half-filled d-orbital.
• D. It has a half-filled p-orbital and completely filled s-and d-orbitals.

Answer 1

Answer: (D)

It has a half-filled p-orbital and completely filled s-and d-orbitals.

Group 15 has a valence shell electronic configuration of $n{s}^{2}n{p}^5$ and period $=4$$meansits$n=4$

thus electronic configuration of element $X$ is $4s^{2}4p^3$

Elements of Group 15 and period 2 onwards are: $N,P,As,Sb,Bi$

Thus $X$ is Arsenic ($As$) and has electronic configuration of: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^3$.

Thus, $s$ and $d-$orbitals are fully-filled and $p-$orbital is half-filled.

Hence, the correct option is $\text{D}$