Concept:Identify the oxide that yields two different oxoacids when it reacts with water.Explanation:Nitrogen dioxide undergoes disproportionation with water.One nitrogen atom is oxidised while another is reduced.This reaction forms two distinct acids:2NO2+H2O→HNO3+HNO2Here, HNO3 is nitric acid and HNO2 is nitrous acid.The other oxides each give only one acid:CO2+H2O→H2CO3 (carbonic acid).SO2+H2O→H2SO3 (sulphurous acid).SO3+H2O→H2SO4 (sulphuric acid).Therefore, only NO2 produces two different acids.Answer:B. NO2