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

On heating, orthophosphorous acid (H3PO3) disproportionates to give:

Answer: H3PO4 and PH3.

  • A H3PO2 and P2O5
  • B H4P2O7 and H2O
  • C P2O3 and H2O
  • D H3PO4 and PH3

Correct answer: D. H3PO4 and PH3

Explanation: H3PO3 (P in +3) disproportionates on heating: 4H3PO3 gives 3H3PO4 (P +5) and PH3 (P -3).

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.

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