\(*\, FBF\) bond angle \(< 120^o\) (\(VSPER\) theory)
\(* \,H N H\) bond angle is less than \(120^o\) but greater than \(109^o28\)' due to back bonding.
\(*\) Due to presence of \(H-\) atom attached to nitrogen this molecule can exhibits intermolecular \(H-\) bonding.
$NO^-_3, CO^{2-}_3 ,CO^-_3 ,SO_3$