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

$1.7 \, g$ of silver nitrate is dissolved in $100 \, g$ of water. Another $0.585 \, g$ of sodium chloride is dissolved in $100 \, g$ of water and added to the first solution,resulting in a chemical reaction. $1.435 \, g$ of silver chloride and $0.85 \, g$ of sodium nitrate are produced. Which law is followed by the above information?

Zinc sulphate contains $22.65\%$ of zinc and $43.9\%$ of water of crystallization. If the law of constant proportions is true,then the weight of zinc required to produce $20\, g$ of the crystals will be ............. $g$.

Pure samples of copper carbonate synthesized in the laboratory and found naturally both contain $51.35 \%$ copper,$38.91 \%$ carbon,and $9.74 \%$ oxygen by weight. This is in accordance with:

When $0.32 \ g$ of sulfur is burnt in air,$224 \ mL$ of $SO_2$ is obtained at $N.T.P$. In another experiment,$SO_2$ is formed by the decomposition of a compound containing $50\%$ sulfur. The results of the given information follow the law of ......

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