Which gas is evolved when PbO2 is treated with conc HNO3?
NO2
O2
N2
N2O
PbO2 is powerful oxidising agent and liberates O2 when treated with acids.
PbO2+2HNO3⟶PbNO32+H2O+12O2PbO2+4HCl⟶PbCl2+2H2O+Cl2