Solution:

The positive worth of ∆rH demonstrates that warmth is assimilated during the development of NO(g).

This implies that NO(g) has higher energy than the reactants (N2 and O2). Henceforth, NO(g) is shaky.

The negative worth of ∆rH demonstrates that warmth is advanced during the development of NO2(g) from NO(g) and O2(g). The item, NO2(g) is settled with least energy.

Henceforth, shaky NO(g) changes to unsound NO2(g).