$A$ 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?

$A$ pure sample of water contains $88.89\%$ of oxygen by mass and $11.11\%$ of hydrogen by mass. This is an example of which law?

Hydrogen combines with oxygen to form $H_2O$ in which $16 \ g$ of oxygen combine with $2 \ g$ of hydrogen. Hydrogen also combines with carbon to form $CH_4$ in which $2 \ g$ of hydrogen combine with $6 \ g$ of carbon. If carbon and oxygen combine together then they will do so in the ratio of

$A$ sample of calcium carbonate has the following percentage composition: $Ca = 40 \%$,$C = 12 \%$,and $O = 48 \%$. According to the law of definite proportion,the weight of calcium in $4 \ g$ of a sample of calcium carbonate from another source will be (atomic weights: $Ca = 40, C = 12, O = 16$).

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 $y$?

The law of multiple proportions was proposed by