Question

An atom of an element has two electrons in the M shell. Give the number of protons in this element.

• A. 10
• B. 14
• C. 12
• D. 15

Answer 1

The correct option is C 12

For M shell value of $n=3$. Thus the electronic configuration is : 2, 8, 2 and atomic number is 12.

No. of neutrons = Atomic mass - No. of protons = 24 - 12 = 12

Thus number of protons $=$ atomic number $=12$.