Question

4 moles of oxygen atoms are present in ____ g of ${\text{N}}{{\text{O}}_2}$ gas.
A.46
B.92
C.69
D.23

Answer 1

We need to calculate the molar mass of nitrogen dioxide. The molecular mass will give us the mass of ${\text{N}}{{\text{O}}_2}$ for 2 moles of oxygen and hence mass for 4 moles can be calculated.

Complete step by step answer:
Let us first find the molar mass of ${\text{N}}{{\text{O}}_2}$ . Molar mass is the mass of 1 mole of the substance. The molar mass of nitrogen is 14 and the molar mass of oxygen is 16.
Hence the molar mass of ${\text{N}}{{\text{O}}_2}$ will be: $14 + 2 \times 16 = 46$
2 moles of atoms of oxygen are contained in 1 mole of ${\text{N}}{{\text{O}}_2}$ gas. We can also say that 2 moles atoms of oxygen are contained in 46 g of ${\text{N}}{{\text{O}}_2}$. For one mole atoms of oxygen mass of ${\text{N}}{{\text{O}}_2}$ will be $23{\text{ g}}$ and for 4 moles it will be $4 \times 23{\text{ g}} = 92{\text{ g}}$.
Hence 4 moles of oxygen atoms are present in 92 g of ${\text{N}}{{\text{O}}_2}$.

Thus, option B is the correct answer.

Additional Information: The chemical formula for nitrogen dioxide is ${\text{N}}{{\text{O}}_2}$. It is one of the oxides of nitrogen. Oxidation state of nitrogen in ${\text{N}}{{\text{O}}_2}$ is $+ 4$. It is a reddish brown gas with a pungent smell and exists in equilibrium with its dimer that is ${{\text{N}}_2}{{\text{O}}_4}$which is yellow brown in colour. ${\text{N}}{{\text{O}}_2}$ is a free radical species that is why it forms dimer. Nitrogen dioxide can be prepared by oxidation of nitrogen monoxide or simply nitric oxide. It also produces an intermediate in the preparation of nitric acid.

Note:
The mixing of ${\text{N}}{{\text{O}}_2}$ or interaction of ${\text{N}}{{\text{O}}_2}$ along with the water, oxygen and other chemical that are present in atmosphere and cause acid rain which ultimately harm the ecosystem, water bodies and aquatic life.