Which of the following statements illustrate the law of multiple proportions?

3.47 g of ${\mathrm{BaCl}}_2$ reacts with 2.36 g ${\mathrm{Na}}_2{\mathrm{SO}}_4$ + to give 3.88 g ${\mathrm{BaSO}}_4$ and 1.95 g NaCl

Hydrogen sulphide contains 5.89% hydrogen, water contains 1 I .l% hydrogen and sulphur dioxide contains 50% oxygen

An element forms two oxides, XO and ${\mathrm{XO}}_2$ containing 50% and 60% oxygen respectively. The ratio of masses of oxygen which combines with 1 g of element is 2 : 3

20 mL ammonia gives l0 volumes ${\mathrm{N}}_2$ and 30 volumes ${\mathrm{H}}_2$ at constant temperature and pressure