Question

Calculate the molecular mass of the following:

(a) $HN{O}_3$

(b) ${\mathrm{CH}}_4$
[2 Marks]

Answer 1

(a) Molecular mass of $HN{O}_3$= (1 × Atomic mass of H) + (1 × Atomic mass of N) + (3 × Atomic mass of O)
= 1 u + 14 u + (3 × 16 u)
= 63 u
[1 Mark]

(b) Molecular mass of ${\mathrm{CH}}_4$ = (1 × Atomic mass of C) + (4 × Atomic mass of H)
= 12 u + (4 × 1 u)
= 16 u
[1 Mark]