Answer: NO 2 (nitrogen dioxide).
- A NO<sub>2</sub> (nitrogen dioxide)
- B N<sub>2</sub>O (laughing gas)
- C NO (nitric oxide)
- D N<sub>2</sub>O<sub>5</sub>
Correct answer: A. NO<sub>2</sub> (nitrogen dioxide)
Explanation: NO<sub>2</sub> reacts with VOCs in sunlight to produce ozone and other irritants forming photochemical smog.

Xenon tetrafluoride (XeF4) has six electron domains around xenon — four Xe–F bonds plus two lone pairs. The lone pairs occupy opposite axial positions, leaving the four fluorine atoms in a square-planar shape (Xe–F ≈ 194 pm). Image: ChemSim, Public Domain, via Wikimedia Commons.
Concept context
Covers the nitrogen family (Group 15), oxygen family (Group 16), halogens (Group 17), and noble gases (Group 18). One of the highest-weightage inorganic chapters in NEET and JEE - includes preparation and properties of HNO₃, H₂SO₄, interhalogens, and xenon compounds.