Which of the following pairs of compounds illustrates the law of multiple proportions?

Which law is illustrated by compounds $H_2O$ and $H_2O_2$ formed from two different elements,$H$ and $O$?

$A$ sample of calcium carbonate $(CaCO_3)$ has the following percentage composition: $Ca = 40\%$,$C = 12\%$,$O = 48\%$. If the Law of Definite Proportions is true,what is the weight of calcium in a $4 \ g$ sample of calcium carbonate?

$1 \, L$ of $N_2$ combines with $3 \, L$ of $H_2$ to form $2 \, L$ of $NH_3$ under the same conditions. This illustrates the:

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?

Two elements $x$ and $y$ have atomic masses $14$ and $16$ respectively. They form a series of five compounds $A, B, C, D, E$ in which the ratio of $x$ to $y$ is $1:2:3:4:5$. If compound $A$ contains $28$ parts by weight of $x$ and $16$ parts by weight of $y$,then in compound $C$,how many parts by weight of $x$ will combine with $24$ parts by weight of $y$?