How many moles of $BaCO_3$ will contain $1.5$ moles of oxygen atoms?

Volume of a gas at $STP$ is $1.12 \times 10^{-7} \ cc$. Calculate the number of molecules in it.

Three $1 \ L$ flasks contain $N_2$,$Ne$,and $O_3$ gases respectively. At the same temperature and pressure,find the ratio of the total number of atoms present.

$A$ 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):

The number of atoms in $558.5 \ g$ of $Fe$ is equal to: [Atomic mass of $Fe = 55.85 \ g/mol$]

What is the number of carbon atoms present in $0.35 \ mol$ of $C_6H_{12}O_6$?