Answer and Explanation:
(a) [tex]Na_2So_4[/tex] : its chemical name is sodium sulfate in which sodium is present as [tex]Na_2^+[/tex] and sulfate is present as [tex]So_4^{2-}[/tex]
(b) [tex]Cu(NO_3)_2[/tex] : Its chemical name is copper nitrate which is a inorganic compound which is mostly crystalline in nature
(c)[tex]Fe_2(Co_3)_2[/tex] : Its chemical name is iron carbonate or ferric carbonate