Blue solid which is obtained on reacting equimolar amounts of two gases at 245K is

When NO and N₂O₄ reacts at low temperature in 1:1 ratio, then N₂O₃ liquid forms which is blue in color.

$2\mathrm{NO}+{\mathrm{N}}_2{\mathrm{O}}_4\stackrel{245 \mathrm{K}}{\to }2{\mathrm{N}}_2{\mathrm{O}}_3$

N₂O₃ is unstable and exists only in low temperature.