Q. In a compound the elements are always present in definite proportions by ______:
Answer: mass
Notes: The law of definite proportion, sometimes called Proust’s law, states that a given chemical compound always contains its component elements in fixed ratio (by mass) and does not depend on its source and method of preparation. For example, oxygen makes up about 8/9 of the mass of any sample of pure water, while hydrogen makes up the remaining 1/9 of the mass.

This question is part of 40000+ General Studies MCQ Series Course on GKToday Android app. Question Number: 61 in Chemistry-4-Compounds in above course in App.