Question

An atom of an element has $4^{th}$ shell as the valence shell with an electron pair in it. The number of electrons in $3^{rd}$ shell is 2 times more than the number of electrons in $2^{nd}$ shell. Identify atomic number.

• A. 24
• B. 25
• C. 27
• D. 28

Answer 1

The correct option is D 28

No. of electrons in $1^{st}$ shell = 2
No. of electrons in $2^{nd}$ shell = 8
No. of electrons in $3^{rd}$ shell = $2\times 8$ = 16
No. of electrons in $4^{th}$ shell = 2
Therefore, total no. of electrons (atomic no.) = 28