Question:
Write the chemical formulae of all the compounds that can be formed by the combination of following ions: $\mathrm{Cu}^{2+}, \mathrm{Na}^{+}, \mathrm{Fe}^{3+}, \mathrm{Cl}^{-}, \mathrm{SO}_{4}{ }^{2-} ; \mathrm{PO}_{4}{ }^{3-}$.
Solution:
For $\mathrm{Cu}^{2+}$ ion : $\mathrm{CuCl}_{2}, \mathrm{CuSO}_{4}, \mathrm{Cu}_{3}\left(\mathrm{PO}_{4}\right)_{2}$
For $\mathrm{Na}^{+}$ion : $\mathrm{NaCl}, \mathrm{Na}_{2} \mathrm{SO}_{4}, \mathrm{Na} 3 \mathrm{PO}_{4}$
For $\mathrm{Fe}^{3+}$ um : $\mathrm{FeCl}_{3}, \mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}, \mathrm{FePO}_{4}$