Question

In the compound A, 1.0g of nitrogen combines with 0.57g of oxygen. In compound B, 2.0g of nitrogen combines with 2.24g of oxygen and in compound C, 3.0g of nitrogen combine with 5.11g of oxygen. These results obey the law of :
A.Multiple proportions
B.Constant proportions
C.Reciprocal proportions
D.None of these

Answer 1

Hint: We can simplify the amount of nitrogen and amount of oxygen present in all three compounds. By considering the ratio of oxygen for constant amounts of nitrogen, we can determine the law obeyed the compound.

Complete step by step answer:
We can state the law of multiple proportions when the same two elements form more than one compound, the different weights of one element which combine with the same weight of the other element are in the ratio of simple small whole numbers.
We can state the law of constant proportion that a given chemical compound constantly comprises its component elements in fixed ratio. It does not depend on its surface and method of preparation/synthesis.
We can state the law of reciprocal proportion if two different elements react separately with a constant mass of a third element, the ratio of the weights in which they do so are either the identical as or a simple multiple of the ratio of the weights in which they combine with each other.
From the given question, we can understand that,
Compound A contains $1.00g$ of nitrogen and $0.57g$ of oxygen.
Compound B contains $2.00g$ of nitrogen and $2.24g$ of oxygen.
Compound C contains $3.00g$ of nitrogen and $5.11g$ of oxygen.
So if we keep the amount of nitrogen as 1 g for all the compounds then,
In Compound A, $1.00g$ of nitrogen combines with $0.57g$ of oxygen.
$1gN = 0.57g{O_2}$
In Compound B, $2.00g$ of nitrogen is combined with $2.24g$ of oxygen. So, $1.00g$ of nitrogen is equal to $1.12g$ of oxygen on simplification.
$1gN = 1.12g{O_2}$
In Compound C, $3.00g$ of nitrogen is combined with $5.11g$ of oxygen. So, $1.00g$ of nitrogen is equal to $1.70g$ of oxygen on simplification.
$1gN = 1.70g{O_2}$
So, Let us consider the ratio of oxygen of all three compounds for the constant amount of nitrogen. Then we would obtain,
Ratio of oxygen = $1:2:3$
This ratio represents the law of multiple proportions.

Therefore, the option (A) is correct.

Note:
We must remember that Dalton's law is the other name for law of multiple proportions. The law is valid till an element exists in one specific isotopic form in all its compounds. When an element is present in the form of different isotopes in its compounds, the law becomes invalid.