(a) `underset("Calcium")(2Ca(s))+underset("Dioxygen")(O_(2)(g)) rarr underset("Calcium oxide")(2CaO (s))`
(b) `underset("Iron")(4Fe(s))+underset("dioxygen")(3O_(2) (g)) overset("Heat")(rarr) underset("Iron oxide")(2Fe_(2)O_(3))`
(c) `underset(("Carbon"),("disulphide"))(CS_(2) (g))+underset("Dioxygen")(3O_(2)(g)) rarr underset(("Carbon"),("dioxide"))(CO_(2))+underset(("Sulphur"),("dioxide"))(2SO_(2))`