Calculate the molar mass of the sulphur and phosphorus molecule.
For sulphur:
Molar mass of S = 32g/mol
Sulphur is made up of 8 sulphur atoms.
Hence, molar mass of sulphur (S8) is:
8 × 32mol/g = 256mol/g
For phosphorus:
Molar mass of P = 31g/mol
Phosphorus molecule is made up of 4 phosphorus atoms.
Hence, molar mass of sulphur (P4) is:
4 × 31mol/g = 124 mol/g