According to the concept of law of multiple proportions, if two elements chemically combine to give two or more compounds, then the weight of one element which combines with the fixed weight of the other element in those compound, bear simple multiple ratios to one another.

The British scientist, John Dalton proposed the Law of Multiple Proportion.

The law of multiple proportions say that if two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers. 

The law of multiple proportions say that If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.
Here, the ratios of oxygen which react with a constant mass of N are $2:3 , 2:1$ and $4:3$ respectively.

The answer is multiple proportion.
When two elements combine to from two or more than two compounds, the weights of one of the element which combine with a fixed weight of the other, bear a simple whole number ratio is the law of multiple proportion and the given example supports the law.

John Dalton discovered the law of multiple proportion.

The law of multiple proportions say that If two elements form more than one compounds between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.

The law of multiple proportions says that, If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.

Atoms of elements combine in the ratio of whole numbers to produce a large number of compound called molecules
For example, one $C$ atom combines with one $O$ atom to form one molecule of $CO$. Also, one $C$ atom combines with two $O$ atoms to form one molecule of $CO _2$.

The law of multiple proportions say that if two elementsform more than one compounds between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers. In $SnCl _2$ and $SnCl _4$, the ratio of the weight of Cl reacting with a constant weight of Sn is 2:1.

According to the law of multiple proportion, when two elements combine with each other to form more than one compound, the weights of one element that combines with fixed weight of the other are in the ratio of small whole numbers.

Law of multiple proportions, statement that when two elements combine with each other to form more than one compound, the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.

According to the law of multiple proportion, when two elements combine with each other to form more than one compound, the weights of one element that combines with fixed weight of the other are in the ratio of small whole numbers.

The law of multiple proportions states that when two elements can combine in different ratios to form different compounds, the masses of the element combining with the fixed mass of another element result in the whole-number ratio. 

Law of multiple proportions states that, when two elements combine to form more than one compound, the weights of the combining elements are in a ratio of small whole numbers.

An element forms to oxides containing different percentages of oxygen this illustrates that a fixed mass of the elements combine to give more than one compound then they would do so in a simple whole number ratio. Hence this illustrates law of multiple proportions.

According to law of multiple proportion, if two elements combine to form more than one compound, then the weight of one element combining with the fixed weight of other, in the two compounds, is in a whole number ratio.

The Law of Multiple Proportion: It was given by Dalton. When one element combines with the other element to form two or more different compounds, the mass of one elements, which combines with a constant mass of the other, bear a simple ratio to one another.
So, $CO,CO _2, C _2O _3$ follows law of multiple proportion.

The law of multiple proportions says that If two elements form more than one compounds between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.

Weights of B that combine with $1.0$ g of A in the compounds X, Y and Z are, respectively,
$\dfrac{0.4}{0.3}=1.33,\ \dfrac{48.0}{18.0}=2.66$ and $\dfrac{159.99}{40.0}=4.00$
Ratio being $1.33:2.66:4.00$ or $1:2:3$ is the simple ratio and this illustrates the law of multiple proportions.

Different proportions of oxygen in the various oxides of nitrogen prove the law of multiple proportions.
According to the law of multiple proportions,
 "if two elements chemically combine with each other forming two or more compounds with different compositions
by mass then the ratios of masses of two interacting elements in the two compounds are small whole numbers".

First case,
$3.2$ g of S combines with $3.2$ g of $O _2$.
$1$ g of S combines with $1$ g of $O _2$.
Second case,
$0.8$ g of S combines with $1.2$ g of $O _2$
$1$ g of S combines with $\dfrac {1.2}{0.8}=1.5$ g of $O _2$
Thus, the ratio of the $O _2$ in both cases which combines with a fixed mass ($1$ g) of $S=1:1.5$ or $2:3$, which is a simple whole number ratio and hence, the law of multiple proportion is verified.

A fixed mass of nitrogen, say $100$ grams, may react with $57.14$ grams of oxygen to produce one oxide, or with $114.28$ grams of oxygen to produce the other. The ratio of the masses of oxygen that can react with $100$ grams of nitrogen is $57.14:114.28$ or  $2:1$, a ratio of small whole numbers.

For hydrogen peroxide, 100 g of sample will contain 5.93 g hydrogen and  $\displaystyle 100 - 5.93 = 94.07$ g oxygen respectively.

The molecules of nitrogen monoxide and nitrogen dioxide differ by a multiple of the mass of one oxygen. The statement can be understood by the concept of the Law of multiple proportion.

Law of Multiple proportions states that if two elements form more than one compound between them, then the ratios of masses of second element which combine with a fixed mass of first element ratios of small whole numbers.

CaCO₃ + 2HCl -----> CaCl₂ + H₂O + CO₂. 
2.5g? g 
Mass of CaCO₃= 40+12+3(16)=52+ 48= 100. 
Molar mass of CaCO₃=100g. 
Mass of CaCl₂= 40 + 2(35.5)= 40+ 71= 111. 
Molar mass of CaCl₂=111g. 
Mass of CaCO₃ (g) Mass of CaCl₂ (g) 
For 100g of $CaCO _3$, 111g of CaCl_2$ is formed.
let for 2.5g of $CaCO_3$, $x$ g of $CaCl_2$ is formed.
Thus, by cross multiplication,

$x=111\times 2.5/100= 2.775g = 2.78g$.

For describing law of multiple proportions, the pair $\displaystyle  NO$ and $\displaystyle  NO _2$ can be used.
According to the law of multiple proportions, if two elements combine to form more than one compound, then the different masses of one element which combine with fixed mass of other element, bear a simple ratio to one another.
In the pair $\displaystyle  NO$ and $\displaystyle  NO _2$, we have two elements N and O that combine to form more than one compound. In all other examples, more than two elements are present.

The law of the multiple proportion was proposed by Dalton.
Law of multiple proportions, statement that when two elements combine with each other to form more than one compound, the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.

The law of multiple proportions state that if two elements form more than one compound between them then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.

the law of multiple proportions.: two elements combine to form more than one compound and the masses of one element that combine with a fixed mass of the other element is in the ratio of small whole numbers. 

In compound A 1 gm of nitrogen combined with 0.57 gm of oxygen and compound B 1 gm of nitrogen combined with 1.12 gm of oxygen and C 1 gm of nitrogen combined with 1.7 gm of oxygen so the fixed amount of nitrogen is 1: 2 :3 so this follows of multiple proportion rule 

The given data is in agreement with Law of multiple proportions.

Given,

$P:H = 3.1 : 0.3 = (3.1 \times : 0.30) \times 2 = 6.2 : 0.6$

$H:O = 0.2 : 1.6 = (0.2 \times 3 : 1.6) \times 3 = 0.6 : 4.8$

$P:O = 6.2 : 4.8 = 3.1 : 2.4 $ (ratio by mass) $= 1.29: 1$

$1.29$ mass $P= 1 $ mass $O$

$x$ mass $P= 16 \ g$ mass $O$

$x= 16 \times 1.29 = 20.64 \ g$ Phosphorous

$= \cfrac {20.64}{31}$ moles Phosphorous

$= 0.66$

$1 \ mole \ O(y) = 0.66 \ mole \ P(x) = \cfrac 23$

$\therefore \ x:y = 2:3 $

$x =2 \ ; \ y=3$