Question

Carbon and oxygen combine to form two oxides, carbon monoxide and carbon dioxide in which the ratio of the weights of carbon and oxygen is respectively 12:16 and 12:32. These figures illustrate the
A. Law of multiple proportions
B. Law of reciprocal proportions
C. Law of conservation of mass
D. Law of constant proportions

Answer 1

Hint:In carbon monoxide, no. of carbon atoms is 1 and no. of oxygen atoms is 1 whereas in carbon dioxide, no. of carbon atoms is 1 and no. of oxygen atoms is 2. Here no. of carbon atoms is fixed as one but no. of oxygen atoms is changed in the two compounds. And the weight of oxygen in both the compounds is in the ratio 16:32. So with this information determine the law illustrated.

Complete step-by-step answer:We are given that carbon and oxygen combine to form two oxides, carbon monoxide and carbon dioxide in which the ratio of the weights of carbon and oxygen is respectively 12:16 and 12:32.
As we can see, the weight of carbon is the same in both the compounds but the weight of oxygen is different as the no. of oxygen atoms is different.
So according to the law of multiple proportions, when two elements combine to form two or more compounds, the masses of one of the elements which combine with the fixed mass of the other element bear a simple whole number ratio.
So here the mass of oxygen is different but the carbon’s mass is fixed in both the compounds.
So the ratio of masses of oxygen is 16:32 which is 1:2 which is a simple whole number ratio.
So the given figures illustrate law of multiple proportions.

Hence, the correct answer is Option A.

Note:Do not confuse between law of multiple proportions and law of definite proportions as the law of multiple proportions is an extension of the latter. Law of definite proportions tells that the ratio of elements present in a compound will remain constant no matter how the compound is prepared.