Answer: White phosphorus (P 4 ).
- A White phosphorus (P<sub>4</sub>)
- B Red phosphorus
- C Black phosphorus
- D Violet phosphorus
Correct answer: A. White phosphorus (P<sub>4</sub>)
Explanation: White phosphorus (P<sub>4</sub>) is the most reactive allotrope; it ignites spontaneously in air at ~34°C.
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.