Question

What is the spin ($m_s$) quantum number of electron $9$?

• A. $0$
• B. $+1/2$
• C. $2$
• D. $-1/2$

Answer 1

Answer: (D)

$-1/2$

The value of $m_s=\frac{1}{2}$ for up spin $(\uparrow )$ and $-\frac{1}{2}$ for down spin $(\downarrow )$ ,electron number $9$ has a down spin hence $m_s=-\frac{1}{2}$ i.e., option D.