$N_2{O}_3$ is an unstable oxide of Nitrogen and it decomposes into $N{O}_{\left(g\right)}$ and $N{O_2}_{\left(g\right)}$ where  $N{O_2}_{\left(g\right)}$ is further dimerise into $N_2{O}_4$ (g) as
i)  $N_2{O}_{3\left(g\right)}\rightleftharpoons N{O}_{2\left(g\right)}+N{O}_{\left(g\right)}{k}_{p1}=3.5bar$
ii)  $2N{O}_{2\left(g\right)}\rightleftharpoons N_2{O}_{4\left(g\right)}{k}_{p2}=$
A flask is initially filled with pure  $N_2{O}_{3\left(g\right)}$ having pressure 3. Partial  pressure of $N{O}_{\left(g\right)}$ was found to be 2 bar