Which of the statements are true about the law of chemical combination?

Potassium combines with two isotopes of chlorine Cl  35 and Cl  37 to form two samples of KCl. Their formation follows the law of definite composition.

Different proportions of oxygen in the various oxides of sulphur prove the law of multiple proportions.

H2O and H2S contain 11.11% hydrogen and 5.88% hydrogen, respectively, whereas SO2 contains 50% sulphur. The above data prove the law of reciprocal proportions.

In the decomposition of NH3,2NH3→∆N2+3H2, the ratio of volumes of NH3, N2,  and H2 , is 2:1:3. The above data proves the Gay Lussac law.