Calculate the molar mass of the following substance and ion.

${\mathrm{P}}_2{\mathrm{O}}_5$

Calculate the amount (in mol) in the following mass:

$8.09 \mathrm{g}$ of aluminium

Calculate the amount (in mol) in the following mass: 

$9.8 \mathrm{g}$ of sulphuric acid

Calculate the amount (in mol) in the following mass: 

$25.0 \mathrm{g}$ of calcium carbonate 

Calculate the amount (in mol) in the following mass: 

$279.94 \mathrm{g}$ of iron(III) sulphate