As due to presence of lone pair of electrons on nitrogen atom, it will activate the ring and it will stabilize intermediate cation at o- and p- positions so here electrophile ${\text{NO}}_2^{+}$attack para position which is better than ortho due to less steric hindrance. As $\mathrm{C}\mathrm{O}$ group is ring deactivating so ortho ,para with respect to it are ignored.