How many neutrons are in an atom of mg 25

Solution

Magnesium (Mg) has atomic number of 12 and mass number-25.
We know that for a neutral atom-
Atomic number (Z) = no. of proton = no. of electron
No. of neutron = Mass number(Z) – Atomic number (A)

For Mg,

No. of proton = no. of electron =12
No. of neutron = Mass number(Z) – Atomic number (A) = 25-12 =13