A magnesium ion, Mg2+, is formed from a magnesium atom, Mg. Which row about the numbers of protons and neutrons in the magnesium ion and in the magnesium atom is correct?

Why the answer for this question is B.

Pls help to explain it. Thank you. ​

The correct row is B.

Explanation:

The formation of the magnesium ion, Mg²⁺, comes from the removal of 2 electrons from the valence shell of the magnesium atom. Since the remotion is of electrons, the nucleus of the atom remains the same, so the number of protons and the number of neutrons does not change.

If the number of proton change, then the atom also change, since the identity of an atom is related to the atomic number which is the same to the proton number.          

Now, if the number of neutrons changes, then we would be in the presence of an isotope of the magnesium atom.        

Therefore, the correct row is B.  

I hope it helps you!                            

since electrons are negative the answer is neagtaive