Question

Among the following pairs of compounds, the one that illustrates the law of multiple proportions is:
a.) $N{{H}_{3}}\text{ and NC}{{\text{l}}_{3}}$
b.) ${{H}_{2}}\text{S and S}{{\text{O}}_{2}}$
c.) $\text{CuO and C}{{\text{u}}_{2}}O$
d.) $\text{C}{{\text{S}}_{2}}\text{ and FeS}{{\text{O}}_{4}}$

Answer 1

Hint:. The compounds that obeys the law of multiple proportion the compounds must have the same type of elements present in both the compounds also the isotopes should not be different to obey the law of multiple proportion.

Complete step by step answer:
The law of multiple proportion states that when two elements combine with each other to form more than one compound, the weight of one element that combines with a fixed weight of the other is in the ratio of small whole numbers. This law was proposed by Dalton in the year 1803.

In the first option $N{{H}_{3}}\text{ and NC}{{\text{l}}_{3}}$
Nitrogen is the same in both the compounds but hydrogen is present in the first compound and chlorine is present in the second compound hence this can not illustrate the law of multiple proportions.

In the second option ${{H}_{2}}\text{S and S}{{\text{O}}_{2}}$
Sulphur is present in both the compounds but hydrogen is present in the first compound and oxygen is present in the second compound hence this pair cannot illustrate the law of multiple proportions.

In the third option $\text{CuO and C}{{\text{u}}_{2}}O$
In both the compounds i.e. $\text{CuO and C}{{\text{u}}_{2}}O$ copper and oxygen are present. And the two different compounds are present in the ratio of 1:2 with the fixed weight of oxygen. Hence this illustrates the law of multiple proportions
So, the correct answer is “Option C”.

Note: No matter how much mass of the two elements will react with each other the product will contain the masses of elements in a certain ratio only. There were other laws given by Dalton other than the law of multiple proportions such as the law of conservation of mass.