Question

When $Pb{O_2}$ reacts with concentrated $HN{O_3}$, the gas evolved is
A. $N{O_2}$
B. ${O_2}$
C. ${N_2}$
D. ${N_2}O$

Answer 1

Hint: The compound lead oxide is a dark brown crystalline powder. It is insoluble in water as well as alcohol. It shows dissolution in a dilute solution of nitric acid, oxalic acid, and
hydrochloric acid. It is used as a strong oxidizing agent.

Complete answer:
In this reaction lead dioxide behaves as a base and on reacting with acid it gives a salt with the
elimination of water. This type of reaction is called acid-base reaction or neutralization reaction.
The reaction of lead dioxide ($Pb{O_2}$) and concentrated nitric acid ($HN{O_3}$) is shown below.
$Pb{O_2} + HN{O_3} \to Pb{(N{O_3})_2} + {H_2}O + {O_2}$
When lead dioxide($Pb{O_2}$) is treated with concentrated nitric acid ($HN{O_3}$) to form lead nitrate$Pb{(N{O_3})_2}$ , water(${H_2}O$) and oxygen(${O_2}$).The compound lead oxide is a strong oxidizing agent. The oxidizing agent is the substance that oxidizes another compound by accepting the electron from the other atom.In this reaction, lead dioxide accepts electrons from nitric acid and thus oxidizing it to form lead nitrate.Thus, when $Pb{O_2}$ reacts with concentrated $HN{O_3}$, the gas evolved is oxygen.

So, the correct answer is Option B.

Note:
Lead dioxide decomposes to give lead oxide.
$Pb{O_2} \to P{b_{12}}{O_{19}} \to P{b_{12}}{O_{17}} \to P{b_3}{O_4} \to PbO$
Lead dioxide is helpful in electrochemistry as it is used to make anode and also used in electroplating of copper metal. Lead dioxide is amphoteric in nature which means it shows property of both acid and base. When lead dioxide reacts with dilute nitric acid, no reaction occurs.
$Pb{O_2} + HN{O_3}(dil) \to \text{No reaction}$