Question

Which of the following is known as anhydride of nitric acid.
(A) ${N_2}{O_3}$
(B) ${N_2}{O_4}$
(C) ${N_2}{O_5}$
(D) ${N_2}{O_{}}$

Answer 1

In order to solve this question we need the information that Anhydride of inorganic acids are usually oxides of non metallic elements which can be found by the dehydration of nitric acid gives anhydride of it.

Complete step-by-step answer: First of all we need to know what anhydride.So anhydride is any chemical compound which we can get by the elimination of water from another compound or in particular we will say here removal of water ( ${H_2}O$ ) from particular acid.Since we are finding the anhydride of nitric acid so we need to know the formula of nitric acid which is $HN{O_3}$.According to the option there is a compound ${N_2}{O_3}$ (dinitrogen trioxide) which when reacted with water forms $HN{O_2}$ (Nitrous acid).According to equation:
${N_2}{O_3} + {H_2}O \to 2HN{O_2}$
Now there are no more oxides of nitrogen which are in the option which gives the components of nitric acid except ${N_2}{O_5}$ (dinitrogen pentoxide).So let's see this how it gives the nitric acid through reaction with water. According to equation:
${N_2}{O_5} + {H_2}O \to 2HN{O_3}$
Here it is clear that the dinitrogen pentoxide on reaction with water gives nitric acid.So by this we can summarize that the removal of water by nitric acid or simply the anhydride of nitric acid will be ${N_2}{O_5}$ .

So the (C) option is correct.

Note: As we have done the above question we are familiar with the anhydride of acid we know that how these forms similarly we can get the anhydride of base which will be mainly the oxides of metal. But there are some exceptions.In this question the oxide of nitrogen are gases in which two of them are toxic for us which are nitric oxide and nitrogen dioxide ( $NO$ and $N{O_2}$ respectively).