Final answer:
The law of definite proportions, also known as the law of constant composition, states that in any given chemical compound, the elements always combine in the same proportion with each other. This is due to the fixed arrangement of atoms in the compound.
Step-by-step explanation:
The law of definite proportions, also known as the law of constant composition, states that in any given chemical compound, the elements always combine in the same proportion with each other by mass. This means that the mass ratio of element G to element H will always remain constant in the compound. For example, if element G has a mass of 10g and element H has a mass of 5g in the compound, the ratio will always be 2:1. This consistent ratio is due to the fixed arrangement of atoms in the compound.