Chapter 2, Problem 49E

For each of the following pairs of ions, write the formula of the compound they will form:

1. ${\text{Ca}}^{2+},{\text{S}}^{2-}$
2. ${\text{NH}}_4{}^{+},{\text{SO}}_4{}^{2-}$
3. ${\text{Al}}^{3+},{\text{Br}}^{-}$
4. ${\text{Na}}^{+},{\text{HPO}}_4{}^{2-}$
5. ${\text{Mg}}^{2+},{\text{PO}}_4{}^{3-}$