Question 1
Calculate the molecular masses of $H_2,O_2,C{l}_2,C{O}_2,C{H}_4,C_2{H}_6,C_2{H}_4,N{H}_3,C{H}_{3}OH$.

i) Molecular mass of $H_2=2\times$ Atomic mass of H
= 2 x 1
= 2 u
ii) Molecular mass of $O_2=2\times$ Atomic mass of O
$=2\times 16$
= 32 u
iii) Molecular mass of $C{l}_2=2\times$ Atomic mass of Cl
$=2\times 35.5$
= 71 u
iv) Molecular mass of $C{O}_2=\text{Atomic mass of C}+2\times \text{Atomic mass of O}$
$=12+2\times 16$
= 44 u
v) Molecular mass of CH_4= Atomic mass of $C+4\times \text{Atomic mass of H}$
$=12+4\times 1$
= 16 u
vi) Molecular mass of $C_2{H}_6=2\times \text{Atomic mass of C}+6\times \text{Atomic mass of H}$
$=2\times 12+6\times 1$
= 30 u
vii) Molecular mass of $C_2{H}_4=2\times \text{Atomic mass of C}+4\times \text{Atomic mass of H}$
$=2\times 12+4\times 1$
= 28 u
viii) Molecular mass of $N{H}_3$ = Atomic mass of $N+3\times \text{Atomic mass of H}$
$=14+3\times 1$
= 17 u
ix) Molecular mass of $C{H}_{3}OH=\text{Atomic mass of C}+4\times \text{Atomic mass of H}+\text{Atomic mass of O}$
$=12+4\times 1+16$
= 32 u