Question

The formation of $S{O_2}$ and $S{O_3}$ illustrates the law of:
(A) Conservation of mass
(B) Definite proportions
(C) Multiple proportions
(D) Gaseous volumes

Answer 1

Hint: In the formation of $S{O_2}$ and $S{O_3}$ we can see that a fixed amount of sulphur (1 atom) reacts with 2 and 3 atoms of oxygen and their mass ratio will be a simple ratio = 2 : 3

Complete step by step answer:
In this question we will first see what these laws given in the options say.

-For (A) Conservation of mass: According to this law “The mass of an isolated system can neither be created nor destroyed, but it can be transformed from one form to another.”
In simple words we can say that in a reaction the mass of the reactants in total should be equal to the mass of the products.

-For (B) Definite proportions: According to this law “A given chemical compound always contains its component elements in a fixed ratio (by mass) and it does not depend on its source and method of preparation.”
For example: Water will always contain an H : O ratio by mass to be (1 : 8), whatever be the source of water.

-For (C) Multiple proportions: This law states that when two elements combine to form more than one compound, the mass of one element that combines with a fixed mass of another element, will always be the ratio of whole numbers.
For example: Let us take two compounds of C and O: CO (Carbon monoxide) and $C{O_2}$ (Carbon dioxide). In these two compounds the ratio of mass of oxygen that combines with same mass of carbon is = 16 : 32 = 1 : 2
Similarly we can take two compounds of S and O: $S{O_2}$ (Sulphur dioxide) and $S{O_3}$ (Sulphur trioxide). In these two compounds we can see that the ratio of mass of oxygen that combines with the same mass of sulphur is = 32 : 48 = 2 : 3 ; a simple ratio. Thus we can say that the formation of $S{O_2}$ and $S{O_3}$ illustrates the law of multiple proportions.

-For (D) Gaseous volumes: This law states that at constant temperature and pressure when gases combine, the volume of the gaseous reactants and products can be expressed as a ratio of small whole numbers.
For example: ${N_2} + 3{H_2} \to 2N{H_3}$ ; here 1 volume of nitrogen reacts with 3 volumes of hydrogen to form 2 volumes of ammonia.
-From the above discussion we have seen that formation of $S{O_2}$ and $S{O_3}$ illustrate the law of multiple proportions.
So, the correct answer is “Option C”.

Note: Sulphur and oxygen combine to form various number of compounds like: $SO$, $S{O_2}$, $S{O_3}$, ${S_7}{O_2}$, ${S_6}{O_2}$, ${S_2}{O_2}$, etc.
Among all sulphur dioxide ($S{O_2}$) a major pollutant is air and is produced by the industries, in volcanoes and in fossil fuel combustion. When it undergoes oxidation under the presence of catalyst $N{O_2}$, it forms ${H_2}S{O_4}$ and thus acid rain occurs.