Question

Which of the following statements is/are correct?

• A. The electronic configuration of $Cr$ is $[Ar]3d^{5}4s^1$ (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 $H{N}_3$ is $-3$

Answer 1

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

$\mathrm{Cr}(Z=24)$
[Ar] $3d^{5}4s^1$
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
$Ag(z=47)$
$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{1}4d^{10}$
23 electrons have a spin of one type and $24$ of the opposite type
The oxidation state of $N$ in $H{N}_3$ is not $-3$ but $-1/3$