Which of the following electron configurations for neutral atoms is correct?

magnesium: 1s22s22p63s23p6

argon: 1s22s22p63s23p6

Answer : The correct option is argon.

Explanation :

Neutral atom : It is defined as an atom has equal number of electrons and protons.

The atomic number of magnesium is 12 that means it has 12 number of protons and 12 number of electrons.

As per given electronic configuration, there are 18 electrons are present in magnesium which is the electronic configuration of argon. So, this is not a neutral atom.

The atomic number of argon is 18 that means it has 18 number of protons and 18 number of electrons. So, this is a neutral atom.