$\begin{array}{1 1}(a) 3H_2N_2O_2 \qquad \underrightarrow{Disproportionation} \qquad HNO_3 +H_2O +2NO\\(b)\;3HNO_3 \qquad \underrightarrow{Disproportionation} \qquad HNO_3 +H_2O +2NO\\(C)\;3HNO_2 \qquad \underrightarrow{Disproportionation} \qquad HNO_3 +H_2O +2NO\\(d) 2HNO \qquad \underrightarrow{Disproportionation} \qquad HNO_3 +H_2O +2NO\end{array} $