When the volume is expressed,what does the law of definite proportions represent?

The combining ratios of hydrogen and oxygen in water and hydrogen peroxide are $1: 8$ and $1: 16$. Which law is illustrated in this example?

Among the following pairs of compounds,the one that illustrates the law of multiple proportions is

When two elements combine to form more than one compound,the masses of one element that combine with a fixed mass of the other element are in a simple whole number ratio.
$(a)$ Is the statement given above correct?
$(b)$ If 'yes',which law does it follow?
$(c)$ Give an example corresponding to this law.

"Mass can neither be created nor destroyed" is the statement of

What weight of $BaCl_2$ is required to react with $24.4 \ g$ of sodium sulfate to produce $46.6 \ g$ of barium sulfate and $23.4 \ g$ of sodium chloride (in $g$)?