Question

Which mixing gives deep brown color?
(A) \[{{\text{N}}_2}{\text{O}} + {\text{O}}_2\]
(B) \[{\text{NO}} + {\text{O}}_2\]
(C) \[{{\text{N}}_2}{{\text{O}}_3} + {\text{O}}_2\]
(D) None of the above

Answer 1

Hint: We are aware that the group 15 includes nitrogen, phosphorus, arsenic, antimony and bismuth. Nitrogen is found to be a different element from the rest of the members of this group particularly due to its size, high electronegativity, absence of d orbitals and high ionization enthalpy.

Complete step by step answer:
Let us check out the compound formed by the nitrogen.
Nitrogen form two types of oxides which are found to be \[{{\text{N}}_2}{{\text{O}}_3}\]and \[{{\text{N}}_2}{{\text{O}}_5}\]
The oxide present in the higher oxidation state of the element is more acidic than lower oxidation state.
 The oxides of the type \[{{\text{N}}_2}{{\text{O}}_3}\]of nitrogen and phosphorus are found to be purely acidic.
After this brief introduction with some of the properties we would now discuss the physical appearance of the oxides. Nitrogen makes a number of oxides in different oxidation states.
The oxides of the type \[{{\text{N}}_2}{\text{O}}\] and \[{\text{NO}}\]of nitrogen is found to be colorless neutral gas
The oxides of the type \[{{\text{N}}_2}{{\text{O}}_5}\]of nitrogen are found to be colorless acidic solid.
Very high temperature along with the lightning causes the gases oxygen and nitrogen to react to form nitric oxide which furthers react with more oxygen to form nitrogen dioxide.
You will see the reaction regarding the above statement as follows:
\[\begin{gathered}
  {\text{N}}_2 + {\text{O}}_2 \to {\text{NO}} \\
  {\text{NO}} + {\text{O}}_2 \to {\text{NO}}_2 \\
\end{gathered} \]
The nitrogen dioxide thus formed is found to be in deep brown in color.
In the other reactions namely
\[{{\text{N}}_2}{\text{O}} + {\text{O}}_2\]
\[{{\text{N}}_2}{{\text{O}}_3} + {\text{O}}_2\]
These reactions are not that feasible to give the reactant and even though if we achieve the conditions needed for the reaction none of them would lead to deep brown color product.
Therefore, the correct answer comes out to be (B) \[{\text{NO}} + {\text{O}}_2\].

Note: You should be very careful about the equations given in the question. You should not think that the same color of the product would result as that of the color of the reactant i.e. the color of the oxide of the nitrogen.