Question

Which of the following statements is/are correct?

• A. The electronic configuration of $Cr$ is $[ Ar ] 3 d^5 4 s^1$ (atomic number of $Cr$ is 24 )
• B. The magnetic quantum number may have a negative value
• C. In silver atom, 23 electrons have a spin of one type and 24 of the opposite type (atomic number of Ag is 47)
• D. The oxidation state of nitrogen in $HN _3$ is $-3$

Answer 1

Answer: (A), (B), (C)

$\operatorname{Cr}(Z=24)$
[Ar] $3 d^5 4 s^1$
This is because $d^5$ is a more stable half-filled configuration. Reasons for the stability of halffilled and fully filled orbitals are symmetry and exchange energy
For every value of $l, m$ can be from $-l$ to $+l$
through 0
${Ag}(z=47)$
$1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 4 s^2 3 d^{10} 4 p^6 5 s^1 4 d^{10}$
23 electrons have a spin of one type and $24$ of the opposite type
The oxidation state of $N$ in $HN _3$ is not $-3$ but $-1 / 3$