How many atoms are present in $9.0\mathrm{g}$ of aluminium?

(Atomic mass of $\mathrm{Al}=27.0\mathrm{u}$)

How many molecules are present in $0.0239\mathrm{g}$ of chloroform $\left({\mathrm{CHCl}}_3\right)$.

(Atomic masses $\mathrm{H}=1.0\mathrm{u},\mathrm{C}=12.0\mathrm{u}, \mathrm{Cl}=35.5\mathrm{u}$)

Calculate the mass of one atom of nitrogen. 

(Atomic masses : $\mathrm{N}=14.0\mathrm{u}, \mathrm{Ag}=108.0\mathrm{u}, \mathrm{O}=16.0\mathrm{u}, \mathrm{H}=1.0\mathrm{u}, \mathrm{C}=12.0\mathrm{u}$)

Calculate the mass of one atom of silver.

(Atomic masses: $\mathrm{N}=14.0\mathrm{u}, \mathrm{Ag}=108.0\mathrm{u}, \mathrm{O}=16.0\mathrm{u}, \mathrm{H}=1.0\mathrm{u}, \mathrm{C}=12.0\mathrm{u}$)

Calculate the mass of one molecule of oxygen.

(Atomic masses: $\mathrm{N}=14.0\mathrm{u}, \mathrm{Ag}=108.0\mathrm{u}, \mathrm{O}=16.0\mathrm{u}, \mathrm{H}=1.0\mathrm{u}, \mathrm{C}=12.0\mathrm{u}$)

Calculate the mass of one molecule of water.

(Atomic masses : $\mathrm{N}=14.0\mathrm{u}, \mathrm{Ag}=108.0\mathrm{u}, \mathrm{O}=16.0\mathrm{u}, \mathrm{H}=1.0\mathrm{u}, \mathrm{C}=12.0\mathrm{u}$)

Calculate the mass of one molecule of benzene $\left({\mathrm{C}}_6{\mathrm{H}}_6\right)$. 

(Atomic masses : $\mathrm{N}=14.0\mathrm{u}, \mathrm{Ag}=108.0\mathrm{u}, \mathrm{O}=16.0\mathrm{u}, \mathrm{H}=1.0\mathrm{u}, \mathrm{C}=12.0\mathrm{u}$)

Calculate the mass of carbon dioxide which contains the same number of molecules as are contained in $40.0\mathrm{g}$ oxygen.

Calculate the number of oxygen atoms present in $88\mathrm{g}$ of ${\mathrm{CO}}_2$. What will be the mass of $\mathrm{CO}$ having the some number of oxygen atoms?