Question

Law of constant composition is same as the law of:
A- Conservation of mass
B- Conversation of energy
C- Multiple proportions
D- Definite proportion

Answer 1

Hint: We know that composition means the ratio of substances in a chemical compound. Constant composition means this composition remains constant throughout the compound. Try to check which option will give the same meaning.

Complete step by step answer:
-We know that a chemical compound consists of 2 or more elements. If we take a fixed amount of this substance it has some type of composition then every part of this compound will have the same type of composition. This composition does not change even for a small amount of substance.
-We will check with the options which will be the same as that of the law of chemical composition. The Law of conservation of mass states that mass can neither be created nor destroyed. Mass of any element remains constant in a chemical reaction. This is not the same as the law of constant proportion.
-The Law of conservation of energy states that energy can neither be created nor destroyed it can only be converted from one form to another form. This law is not the same as the law of constant proportion.
-Law of multiple proportions states about 2 or more elements composition in more than compound. Whereas the law of constant proportion states about the composition of elements in one compound.
-Law of definite proportion states that the proportion of elements will be throughout the substance which is the same as that of the law of constant proportion.

Therefore option D is correct.

Note: Law of chemical composition is obeyed in solids. Where unit cells have the same composition and they are distributed all over the crystal. Similarly, gases and liquids obey the law of constant composition.