Answer:
(b) Group 2
Step-by-step explanation:
The number of electronic configuration of magnesium is 2,8,2 so the number of electron in the last shell of magnesium is 2. We know the number of electrons in the last shell is the same as the ground number. However the electronic configuration 3s² identifies that magnesium belongs to group 2. The coefficient 3 identifies that magnesium is in period 3, s mean the last electrons of magnesium are in s sub shell and the power 2 means that magnesium is in group 2