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

When $3 \ g$ of a hydrocarbon is burnt in the presence of sufficient oxygen,it produces $8.8 \ g$ of $CO_2$ and $5.4 \ g$ of $H_2O$. This process is an example of which law?

The following data are obtained when dinitrogen and dioxygen react together to form different compounds:

Mass of dinitrogen	Mass of dioxygen
$(i) \ 14 \ g$	$16 \ g$
$(ii) \ 14 \ g$	$32 \ g$
$(iii) \ 28 \ g$	$32 \ g$
$(iv) \ 28 \ g$	$80 \ g$

$(a)$ Which law of chemical combination is obeyed by the above experimental data? Give its statement.
$(b)$ Fill in the blanks in the following conversions:
$(i) \ 1 \ km = \dots \ mm = \dots \ pm$
$(ii) \ 1 \ mg = \dots \ kg = \dots \ ng$
$(iii) \ 1 \ mL = \dots \ L = \dots \ dm^{3}$

Among the following pairs of compounds,the one that illustrates the law of multiple proportions is

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:

Atoms combine in chemical reactions to form: