Question

Formulae of ammonium sulfate?

Answer 1

`(NH_4)_2SO_4`

Explanation:

Sulfate ion is formally...`SO_4^(2-)`.

Ammonium ion is formally...`NH_4^(+)`...

And so we draft in appropriate anions, and cations to form a neutral salt...`(NH_4)_2SO_4`.