The number of oxygen atoms in $4.4 \ g$ of $CO_2$ is approximately ........ $\times 10^{23}$.

What is the number of moles of oxygen atoms and the number of moles of $N$ atoms respectively present in one mole of thymine?

How many moles of carbon atoms are present in $3.6 \ kg$ of carbon?

$6.02 \times 10^{20}$ molecules of urea are present in $100 \ mL$ of its solution. The concentration of solution is $.... M$.

The mass of $2 \times 10^{22}$ nitrogen atoms is ..... grams.

Which gas among the following contains the maximum number of molecules at $STP$? (Molar masses in $g \ mol^{-1}$: $CO_{2}=44, Ar=39.9, CH_{4}=16, O_{2}=32$)