(a) Quick lime: Quick lime is calcium oxide (CaO) and the elements present are calcium and oxygen.
(b) Hydrogen bromide: Hydrogen bromide (HBr) consists of elements hydrogen and bromine.
(c) Baking powder: Baking powder or sodium bicarbonate (NaHCo3) consists of elements sodium, hydrogen, carbon and oxygen.
(d) Potassium sulphate: Potassium sulphate (K2SO4) consists of elements potassium, sulphur and oxygen.