Question

N2O3 reacting with water gives Hno2. Is h3no3 as product possible?

Answer 1

The anhydride of HNO3 is N2O5 (nitrogen pentoxide).  

N2O3 is the anhydride of HNO2 (nitrous acid).

so,

N2O3 disolve in water and gives HNO2.

N2O5 disolve in water and gives HNO3.