Different proportions of oxygen in the various oxides of nitrogen prove the

Carbon and oxygen combine to form two oxides,carbon monoxide and carbon dioxide,in which the ratio of the weights of carbon and oxygen is respectively $12 : 16$ and $12 : 32$. These figures illustrate the:

$2 \ g$ of hydrogen combine with $16 \ g$ of oxygen to form water and with $6 \ g$ of carbon to form methane. In carbon dioxide,$12 \ g$ of carbon are combined with $32 \ g$ of oxygen. These figures illustrate the law of:

Which of the following pairs of compounds does not demonstrate the law of multiple proportions?

Statement $1$: The mass ratio of hydrogen to oxygen in water obtained from rivers,wells,lakes,or seas is always $1:8$.
Statement $2$: In $1799$,the scientist Joseph Proust proposed the Law of Definite Proportions.

Which law is followed by the different proportions of oxygen in various oxides of nitrogen?