laws of chemical combination explanation with answers most important i want to know is law of reciprocal

(1) Law of conservation of mass:

It was proposed by Lavoisier and verified by Landolt. According to this law, Matter is neither created nor destroyed in the course of chemical reaction though it may change from one form to other.  The total mass of materials after a chemical reaction is same as the total mass before reaction.    

(2) Law of constant or definite proportion:

It was proposed by Proust. According to this law, A pure chemical compound always contains the same elements combined together in the fixed ratio of their weights whatever its methods of preparation may be.

(3) Law of multiple proportion:

It was proposed by Dalton and verified by Berzelius. According to this law, When two elements A and B combine to form more than one chemical compounds then different weights of A, which combine with a fixed weight of B, are in proportion of simple whole numbers.     

(5) Gay-Lussac’s law:

It was proposed by Gay–Lussac and is applicable only for gases. According to this law, When gases combine, they do so in volumes, which bear a simple ratio to each other and also to the product formed provided all gases are measured under similar conditions. The Gay-Lussac’s law, was based on experimental observation.

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