Question 2

Bond angles: NO2⁻ ≈ 115° (lone pair on N), NO3⁻ = 120°, NO2 ≈ 134° (single unpaired electron), NO2⁺ = 180° (linear). Order: NO2⁻ < NO3⁻ < NO2 < NO2⁺, which is option (B).

No written reasoning was returned for this item.

**Evaluating bond angles** I need to answer a question related to the correct order of the ONO bond angle in several species: NO2+, NO2, NO3−, and NO2−. Let's take a closer look at the options. Option A suggests an increasing order: "NO2+ < NO2 < NO3− < NO2−." I know that nitrogen compounds have varied geometries. For example, NO2+ is linear with a bond angle of 180°, while NO3− has a trigonal planar configuration with angles around 120°. The neutral NO2 has a bent shape with angles around 134°. **Finalizing bond angle order** Nitrogen dioxide indeed has a bent structure with an O-N-O angle of 134.3°, which is greater than the nitrate angle of 120° and less than the nitronium angle of 180°. The nitrite ion (NO2−) has a bent angle around 115° due to lone pair repulsion. So the increasing order of angles should be: NO2− (115°) < NO3− (120°) < NO2 (134°) < NO2+ (180°). This corresponds to option B. Now, I'll prepare the output as a JSON object without any extra text.