What is the weight in $g$ of $2.01 \times 10^{23}$ molecules of $CO$?

Calculate the number of moles in $11.2 \ L$ of oxygen gas at $STP$.

$A$ sample of $[Cu(NH_3)_4]SO_4$ contains $2.4 \times 10^{24}$ ammonia molecules. The moles of $[Cu(NH_3)_4]SO_4$ in the given sample will be:

Calculate the number of atoms of oxygen present in $176 \ g$ of $CO_2$.

$A$ mixture has $18 \ g$ of water and $414 \ g$ of ethanol. The mole fraction of water in the mixture is (assume ideal behavior of the mixture):

Calculate the following for $3 \ mol$ of ethane $(C_2H_6)$:
$(i)$ Number of moles of carbon atoms
$(ii)$ Number of moles of hydrogen atoms
$(iii)$ Number of molecules of ethane