Question

The values of four quantum numbers of valence electron of an element are $n=4,l=0,m=0$ and $s=+\frac{1}{2}.$ The element is:

• A. K
• B. Ti
• C. Na
• D. Sc

Answer 1

Answer: (A)

Four quantum numbers are $n=4$ $l=0$ $m=0$ $s=+\frac{1}{2}$ $n=4$ indicates that the valence electron present in 4th shell (4th period) $l=0$ indicates that the valence electron is present in s-subshell. indicates that the valence electron is present in orbital of s-subshell. $s=+\frac{1}{2}$ indicates that the spining of electron in orbital is clockwise. So, from the above discussion it is clear that valence electron is present in 4^ subshell as $4s^1.s^1$ indicates that the element is present in IA group. So, the element present in 4th period and IA group is potassium (K).