Question

a compound contain 16% sulphur by mass and 4% oxygen by mass find it's minimum molecular mass

Answer 1

Since S makes up 16% of its mass, that is:-
Mass of S = Total mass * 16%, then
Total mass = Mass of S / 16% = 32.1/16% = 200
So its mass is 200 grams.
Since S makes up 4% of its mass, that is:
Mass of O = Total mass * 4%, then
Total mass = Mass of O/ 4% = 16/4% = 400
minimum molar mass of a substance = 200+400 = 600