Give the chemical formulae for the following compounds and compute the ratio by mass of the combining elements in each one of them. (You may use appendix-III).

(a) Ammonia

(b) Carbon monoxide

(c) Hydrogen chloride

(d) Aluminium fluoride

(e) Magnesium sulphide

(Aluminium fluoride a) Ammonia = NH₃

The atomic mass of N = 14

The atomic mass of H = 1

Thus, Ratio by mass = N : H × 3

= 14 : 1 × 3

= 14:3

(b) Carbon monoxide = CO

The atomic mass of C = 12

The atomic mass of O = 16

Thus, Ratio by mass = C:O

= 12:16

= 3:6

(c) Hydrogen chloride = HCl

The atomic mass of H = 1

The atomic mass of Cl = 35.5

Thus, Ratio by mass = H : Cl

= 1:35.5

(d) Aluminium fluoride = AlF₃

The atomic mass of Al = 27

The atomic mass of F = 19

Thus, Ratio by mass = Al : F × 3

= 27 : 19 × 3

= 27 : 57

= 9 : 19

(e) Magnesium sulphide = MgS

The atomic mass of Mg = 24

The atomic mass of S = 32

Thus, Ratio by mass = Mg : S

= 24 : 32

= 3 : 4