Calculate the molar mass of the following substances: (a) Ethyne, C2H2 (b) Sulphur molecule, S8 (c) Phosphorus molecule, P4 (Atomic mass of phosphorus = 31) (d) Hydrochloric acid, HCl (e) Nitric acid, HNO3

(a) Ethyne (C2H2) =2×Mass of C atom+2×Mass of H atom=2×12+2×1=24+2=26 g/mol
(b) Sulphur dioxide (S8)=8×Mass of sulphur atom=8×32=256 g/mol
(c)P4=4×Mass of P atom=4×31=124 g/mol
(d)HCl=1×Mass of H atom+1×Mass of Cl atom=1+35.5=36.5 g/mol
(e)HNO3=1×Mass of H atom+1×Mass of N atom+3×Mass of O atom=1×1+1×14+3×16=63 g/mol