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Question: Answered & Verified by Expert
An organic compound ‘A’ is oxidized with Na2O2 followed by boiling with HNO3. The resultant solution is then treated with ammonium molybdate to yield a yellow percipitate. Based on a above observation, the element present in the given compound is:
ChemistryPractical ChemistryJEE MainJEE Main 2019 (12 Apr Shift 1)
Options:
  • A Fluorine
  • B Phosphorus
  • C Nitrogen
  • D Sulphur
Solution:
2360 Upvotes Verified Answer
The correct answer is: Phosphorus

The phosphorus containing organic compounds are detected by 'Lassaigne's test' by heated with an oxidizing agent (sodium peroxide). The phosphorus present in the compound is oxidised to phosphate.

The solution is boiled with nitric acid and then treated with ammonium molybdate to produced canary yellow precipitate. 

Phosphorus gets oxidised when it is treated with fuming conc. HNO3.
Na3PO4+3HNO3H3PO4+3NaNO3

Phosphoric acid is used along with molybdenum compound for the identification of Magnesium.

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