What is the total number of neutrons present in $1.7 \ g$ of ammonia $(NH_3)$?

$A$ thin layer of cobalt is deposited on a plate with a total area of $0.5 \ m^2$ and a thickness of $0.005 \ cm$. How many cobalt atoms are deposited on the plate? (Density of cobalt $= 8.9 \ g \ cm^{-3}$,Atomic mass of $Co = 59 \ g \ mol^{-1}$)

$8 \ g$ of $O_2$ has the same number of atoms as that in:

What is the number of molecules in $5.23 \ g$ of glucose $(C_6H_{12}O_6)$?

In which of the following pairs do $1 \text{ g}$ of each contain the same number of molecules?
$(I)\, N_2O$ and $CO$               $(II)\,N_2$ and $CO_2$
$(III)\, N_2$ and $CO$                $(IV) \,N_2O$ and $CO_2$

Find the volume at $STP$ and mass of $6.022 \times 10^{23}$ molecules of $O_2$. (Molar volume $= 22.4 \ L$)