(a) Calculate the relative molecular mass of water (H2O).

(b) Calculate the molecular mass of HNO3.

(a) Atomic mass of hydrogen = 1u, oxygen = 16 u
So the molecular mass of water, which contains two atoms of hydrogen and one atom of oxygen is = 2 1+ 116 = 18 u

(b) The molecular mass of HNO3 = the atomic mass of H + the atomic mass of N+ 3 the atomic mass of O
= 1 + 14 + 48 = 63 u