Volume occupied by one molecule of water (density $= 1 \ g \ cm^{-3}$) is ...... $ \times 10^{-23} \ cm^3$.

The weight of $112 \ cm^3$ of $CH_4$ gas at $STP$ is ...... $g$.

At the same temperature,$10 \ dm^3$ of $N_2$ gas and $10 \ dm^3$ of gas $x$ contain the same number of molecules. What is the gas $x$?

From $44 \ mg$ of $CO_2$,$2 \times 10^{20}$ molecules of $CO_2$ are removed. The number of molecules of $CO_2$ left are (Given $N_A = 6 \times 10^{23}$):-

How many moles of magnesium phosphate $Mg_3(PO_4)_2$ contain $0.25$ moles of oxygen atoms?

In $3$ moles of ethane $(C_{2}H_{6})$,calculate the following:
$i.$ Number of moles of carbon atoms.
$ii.$ Number of moles of hydrogen atoms.
$iii.$ Number of molecules of ethane.