Question

State and explain law of multiple proportions with the help of an example.

Answer 1

Hint: Law of multiple proportions was announced by an English chemist John Dalton. It is also called Dalton's Law.

Complete step by step answer:
The Law of Multiple proportion acted as the most powerful argument in support of Dalton’s theory that matter consists of indivisible atoms.
 It states that when two same elements combine to form more than one compound, the mass of one element that combines with a fixed mass of the other element are always in the ratios of whole numbers. Let us see an example:
Consider the elements carbon and oxygen. We can combine it to form the compound, carbon dioxide. Every sample of carbon dioxide contains 32.0 g of oxygen for every 12.0 g of carbon.
We can form another compound that is produced from the combination of carbon and oxygen, called carbon monoxide. Every sample of carbon monoxide contains 16.0 g of oxygen for every 12.0 g of carbon.
The ratio of mass of oxygen in carbon monoxide to the mass of oxygen in carbon dioxide is 16:32 = 1:2.
Carbon dioxide contains twice the amount of oxygen present in the carbon monoxide.
Here we got the ratio of oxygen in different compounds in whole numbers. Thus it justifies the law of multiple proportions.

Note: Do not confuse between law of multiple proportions and law of definite proportions. Law of definite proportions states that every chemical compound contains fixed and constant proportions (by mass) of its constituent elements.