WAEC - Chemistry (2009 - No. 29)

Normal salts, also known as neutral salts, are formed through the complete neutralization of a strong acid and a strong base, where the ionizable hydrogen atoms of the acid are completely replaced by a metallic or ammonium ion. 

Trioxonitrate(v) acid will only form one type of salt because it is a monobasic acid i.e. it contains only one replaceable hydrogen atom.