Respuesta :
Cations mix with anions, so you know NH4+ won't mix with K+ and SO4(2-) won't miix with F-. For the reason that NH4+ and F- together have single charges, they'll mix in a 1:1 ratio, NH4F. There's two charges on SO4(2-), so it'll need two K+ to mix with, K2SO4.
Make sure you include these points:
The atoms in each ion are bonded together covalently to form a single unit.
The charge is distributed over the entire ion.
The formula of ammonium fluoride is NH4F.
The formula of potassium sulfate is K2SO4.