The Lewis structure of NO₂- is:
That the nitrite ion. N has a lone pair of electrons (it has gain one because of the negative charge). It is bonded to two atoms of O. One atom of O has 2 lone pairs (since it has a double bond) and the other atom of O has 3 lone pairs (and a single bond).
The molecular structure of this ion is Bent. Why this geometry? Because of the lone pair of electrons of N. There is some repulsion between this electrons and the other ones. So these atoms make this arrangemente to minimize the electron repulsion.
Answer: Bent.