Which of the following nitrogen-based polyatomic ions exhibits a linear geometry?

Step-by-step solution

The geometry of polyatomic ions can be determined using VSEPR theory by evaluating the steric number (number of bonds + number of lone pairs on the central atom). For NO ₂⁻ , the central nitrogen atom forms two bonds and has one lone pair. The steric number is 2 + 1 = 3 , corresponding to sp^2 hybridization. The presence of one lone pair results in a bent (V-shaped) geometry. For NO ₃⁻ , the central nitrogen atom forms three bonds and has zero lone pairs. The steric number is 3, corresponding to sp^2 hybridization