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🧪 Chemistry  ·  p-Block Elements (Groups 15 to 18)  ·  NEET & JEE

Which oxide of nitrogen is responsible for photochemical smog?

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: a central xenon bonded to four fluorine atoms in a square-planar arrangement with two lone pairs above and below, Xe-F bond length 194 pm.

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.

Read the full p-Block Elements (Groups 15 to 18) notes →