Question

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:
(A) Law of multiple proportion
(B) Nuclear fusion
(C) Vander Waals forces
(D) Graham’s Law of Diffusion (Effusion)
(E) Triple point

Answer 1

Hint :The chemical formula for nitrogen monoxide is $ NO\; $ and for nitrogen dioxide is $ NO_2 $ . Here, we are concerned with the compounds at the molecular level and the laws governing the formation of molecules from atoms or compounds from elements. Hence, whichever law governs the formation of compounds is the required answer.

Complete Step By Step Answer:
Let us consider the given laws one by one;
Law of multiple proportion: “If two molecules can combine to form more than one compounds, the masses of one element that react with the fixed mass of the other element, are in a ratio of a small whole number.”
Nuclear fusion: “The process in which two or more lighter atomic nuclei combine to form one or more atomic nuclei and subatomic particles. There will be a mass difference between the reactants and the products, which results in release of immense energy.”
Vander Waals forces: “The distance dependent interaction between the atoms or the molecules including the attractions, repulsions and other intermolecular forces which are weaker than the ionic or covalent bond.”
Graham’s law of effusion: “The rate of effusion or diffusion (movement of anything from a region of higher concentration to the region of lower concentration) of the gas is inversely proportional to the square root of the mass of its particles.”
Triple point: “A particular temperature and pressure at which all three phases – solid, liquid and gas of a particular substance can co-exist in equilibrium.”
From all the laws explained above, only the law of multiple proportions is concerned with the compound formation from different elements.
Let us prove the given fact by Law of multiple proportions;
For both the compounds Nitrogen monoxide $ NO\; $ and Nitrogen dioxide $ NO_2 $ , we can see that the mass or amount of nitrogen remains fixed, while the amount or mass of oxygen changes
Let us express the reaction for formation of both compounds, with the atomic mass related to the amount of gas as shown below
 $ \dfrac{1}{2}{{N}_{2}}(Nitrogen,14g)+\dfrac{1}{2}{{O}_{2}}(Oxygen,16g)=NO(Nitrogen\;oxide,30g) $
 $ \dfrac{1}{2}{{N}_{2}}(Nitrogen,14g)+{{O}_{2}}(Oxygen,32g)=N{{O}_{2}}(Nitrogen\;dioxide,46g) $
From the Law of multiple proportions, the masses of oxygen that react with the fixed mass of nitrogen are in the ratio $ 16:32\; $ or $ 1:2\; $ . Hence, the mass of oxygen in Nitrogen oxide and Nitrogen dioxide differ only by a multiple.
Hence, the correct answer is Option $ (A) $ .

Note :
The nuclear fission is concerned with the atoms combining at the nucleus level, and does not depend on the ratio in which molecules are formed. The Vander waals force deals with the intermolecular forces between molecules, which are of no concern here. Graham's law of effusion deals with the movement of a gas, which is not shown or required here. Triple point is concerned with a specific temperature and pressure at which all phases coexist, but here there is no change of phase or temperature or pressure.