NaOH + HCl $$\to$$ NaCl + H₂O

CaO + H₂O $$\to$$ Ca(OH)₂

2Mg + O₂ $$\to$$ 2MgO

Na₂SO₄ + BaCl₂ $$\to$$ BaSO₄ + 2NaCl

Ammonium nitrate

Ammonium sulphide

Ammonium phosphate

Ammonium sulphate

CaSO₄ . 2H₂O

Ca₂SiO₄

2CaSO₄ . H₂O

CaSO₄

A given compound always contains exactly same proportion of elements.

When gases combine in a reaction, they do so in a simple ratio by volume, provided all gaseous are at room temperature.

Matter can neither be created nor be destroyed.

Equal volumes of all gases at same temperature and pressure contain equal number of molecules.