C is the answer.
It says on the third picture that Bohr refined Rutherford's model by giving distinct orbits for the electrons with distinct radii.
An ionic equation contains two ions in the full equation
No
Magnesium Chloride is MgCl2
The method I use to name ionic compounds is 'swap and drop'
Mg oxidation number is +2 and Cl oxidation number is -1
Mg^2+ Cl^-1
'swap'
Mg^1 Cl^2
'drop'
MgCl2