(a) If two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in whole-number ratio and this statement is true.
(b) This statement is according to the Law of multiple proportions.
(c) Example of Law of multiple proportions:
H and O reacts to produce water and hydrogen peroxide
Reaction Involved –
H2 + 1/2O2 → H2O
H2 + O2 → H2O2
Masses of oxygen is in the ratio of either 16:32 or 1