The number of water molecules in $1 \, L$ of water is = ............

The number of atoms present in $0.1 \ mol$ of a triatomic gas is: $(N_A = 6.022 \times 10^{23} \ mol^{-1})$

If $10^{21}$ molecules are removed from $200 \, mg$ of $CO_2$,then the number of moles of $CO_2$ left is .....

What is the number of hydrogen atoms present in $5.4 \ g$ of urea?

What is the number of moles of nitrogen atoms present in one mole of cytosine?

$K-40$ is a natural radioactive isotope which constitutes $0.012\%$ of natural potassium. If a cup of milk contains $370 \ mg$ of $K$,how many atoms of $K-40$ are ingested?