"$A$ given compound always contains the same proportion of elements" is a statement of $-$

Gay-Lussac's law of gaseous volumes is derived from $.......$.

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 ............. $g$.

According to Dalton’s atomic theory,an atom

Zinc sulfate crystals contain $22.65\%$ of zinc and $43.9\%$ of water. If it follows the law of definite proportions,how many grams of $Zn$ are required to obtain $20 \, g$ of crystals?

The law of definite proportions is not applicable to nitrogen oxides because