Question

The relative molecular masses of hydrogen, nitrogen, oxygen, and chlorine are double their relative atomic masses.
(a)- True
(b)- False

Answer 1

The atomic formula of hydrogen, nitrogen, oxygen, and chlorine are $H,\text{ }N,\text{ }O,\text{ and }Cl$ respectively, and the molecular formulas of hydrogen, nitrogen, oxygen, and chlorine are ${{H}_{2}},\text{ }{{N}_{2}},\text{ }{{O}_{2}},\text{ and }C{{l}_{2}}$.

Complete step by step answer:
Hydrogen is the element of s-block. Its atomic number is 1. The relative atomic mass of hydrogen is$1.0079\text{ g}$. The electronic configuration of hydrogen is $1{{s}^{1}}$. So, one more electron is needed to complete its octet. So, in the molecular form, there are 2 hydrogen atoms.
The structure of molecular hydrogen is $H-H$. The molecular mass of hydrogen is$2.016\text{ g}$. The molecular mass of hydrogen is double of the atomic mass of hydrogen.
Nitrogen is the element of p-block. Its atomic number is 7. The relative atomic mass of nitrogen is$14.007\text{ g}$. The electronic configuration of nitrogen is $1{{s}^{2}}2{{s}^{2}}2{{p}^{3}}$. So, it needs three more electrons to complete its octet. So, in the molecular form, there are 2 nitrogen atoms.
The structure of molecular nitrogen is: $N\equiv N$. The molecular mass of nitrogen is$\text{28}\text{.014 g}$. The molecular mass of nitrogen is double of the atomic mass of nitrogen.
Oxygen is the element of p-block. Its atomic number is 8. The relative atomic mass of oxygen is$\text{15}\text{.999 g}$. The electronic configuration of oxygen is $1{{s}^{2}}2{{s}^{2}}2{{p}^{4}}$. So, two more electrons are needed to complete its octet. So, in the molecular form, there are 2 oxygen atoms.
The structure of molecular oxygen is $O=O$. The molecular mass of oxygen is $31.998\text{ g}$. The molecular mass of oxygen is double of the atomic mass of oxygen.
Chlorine is the element of p-block. Its atomic number is 17. The relative atomic mass of chlorine is $\text{35}\text{.453 g}$. The electronic configuration of chlorine is $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{5}}$. So, it needs one more electron to complete its octet. So, in the molecular form, there are 2 chlorine atoms.
The structure of molecular chlorine is $Cl-Cl$. The molecular mass of chlorine is$\text{70}\text{.906 g}$. The molecular mass of chlorine is double of the atomic mass of chlorine.
Hence, the statement “The relative molecular masses of hydrogen, nitrogen, oxygen, and chlorine are double their relative atomic masses” is true.

Note: As the number of atoms increases in its molecular formula, the molecular mass also increases with the number of atoms. For example, the atomic mass sulfur is $32\text{ g}$ and in the molecular formula of sulfur has 8 sulfur atoms. The molecular mass of sulfur will be $8\text{ x 32 = 256 g}$.