Question

The four quantum of last electron of an atom are $4,0,0,+\frac{1}{2}$ then atomic number of that element could be?

• A. $24$
• B. $55$
• C. $36$
• D. $37$

Answer 1

The correct option is A $24$

Solution :

n=4 , l=0, m=0 and x= +$\frac{1}{2}$

This set represents that the last electron enters in a 4s orbital.

Nearest element to satisfy this is chromium

$Cr=\left[Ar\right]3d^{5}4s^1$

No of electron = 24