Question

Calculate the minimum and the maximum number of electrons which may have magnetic quantum number, $m=+1$ and spin quantum number, $s=-\frac{1}{2}$ in chromium $\left(Cr\right)$.

• A. $0,1$
• B. $1,2$
• C. $4,6$
• D. $2,3$

Answer 1

The correct option is D $2,3$

Both $2p$ and $3p$ subshells are completely filled.
Hence, out of 6 electrons in the $2p$ subshell one electron must have $m=+1$ and $s=-\frac{1}{2}$.
Similarly, out of 6 electrons in the $3p$ subshell one electron must have $m=+1$ and $s=-\frac{1}{2}$.

But in $3d-subshell$ an electron having $m=+1$ may have spin quantum number $-\frac{1}{2}$ or $+\frac{1}{2}$.
Therefore, the minimum and the maximum number of electrons with configuration $m=+1$ and $s=-\frac{1}{2}$ are 2 and 3 respectively.