Who proposed the Law of Multiple Proportions?

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

From the given information, select the suitable law of chemical combination:

Cupric Carbonate	% of $Cu$	% of $C$	% of $O$
Natural sample	$51.35$	$9.74$	$38.91$
Synthetic sample	$51.35$	$9.74$	$38.91$

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 $g$)?

$45.4 \ L$ of dinitrogen reacts with $22.7 \ L$ of dioxygen to form $45.4 \ L$ of nitrous oxide. For the reaction $2N_{2(g)} + O_{2(g)} \to 2N_2O_{(g)}$,identify the law followed and state the law.

Which of the following examples illustrates the Law of Multiple Proportions?