To determine the maximum bond angle at nitrogen in the given species, we need to consider the molecular geometry around the nitrogen atom.$\\$Let's analyze each option:$\\$• Option 1: $$NO$_2^- \\$The $$NO$_2^-$ ion has a bent shape due to the presence of a lone pair on nitrogen.$\\$The bond angle is less than $120^\circ$ due to lone pair-bond pair repulsion.$\\$• Option 2: $$NO$_2^+ \\$The $$NO$_2^+$ ion has a linear shape because there are no lone pairs on nitrogen.$\\$The bond angle is $180^\circ. \\$• Option 3: $$NO$_3^- \\$The $$NO$_3^-$ ion has a trigonal planar shape with bond angles of $120^\circ. \\$• Option 4: $$NO$_2 \\$The $$NO$_2$ molecule has a bent shape due to the presence of a lone electron on nitrogen.$\\$The bond angle is slightly less than $120^\circ. \\$Among the given options, the $$NO$_2^+$ ion has the maximum bond angle at nitrogen, which is $180^\circ. \\$Therefore, the correct option is 2.