How many moles of nitrogen atoms are present in $8 \ g$ of ammonium nitrate (in $mol$)?

Find the number of millimoles for $0.160 \ g$ sodium hydroxide.

The number of water molecules in $250\, mL$ of water is closest to $.....\, \times 10^{23}$.
[Given: density of water is $1.0\, g\, mL^{-1}$; Avogadro's number $= 6.023 \times 10^{23}$]

The number of molecules and atoms present in $1.2 \ g$ of ozone $(O_3)$ are respectively:

One mole of carbon atom weighs $12 \; g$. The number of atoms in it is equal to: (Mass of one carbon-$12$ atom is $1.9926 \times 10^{-23} \; g$)

The volume of a gas in a discharge tube at $STP$ is $1.12 \times 10^{-7} \ mL$. What is the number of molecules of the gas in the tube?