Pick the wrong statement about phosphorus and nitrogen products — Identify the statement that is NOT correct.
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AYellow phosphorus, the most reactive allotrope, is transported under water for safety
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BApatite, the principal mineral in phosphate rock, has the general composition Ca10(PO4)6(F, Cl, OH)
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CUrea is more hygroscopic than ammonium nitrate
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DNitrogen fixation refers to bringing atmospheric nitrogen into combined (compound) form
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EAll statements are correct
Answer
Correct Answer: Urea is more hygroscopic than ammonium nitrate
Explanation
Introduction:Handling and classification of fertilizer materials depend on accurate chemical knowledge—from allotropes and mineral compositions to storage properties like hygroscopicity. This question asks you to spot the erroneous statement among commonly cited facts.
Given Data / Assumptions:
- Yellow (white) phosphorus is highly reactive and pyrophoric.
- Apatite is the main mineral form of phosphate rock used for phosphorus processing.
- Urea and ammonium nitrate are both nitrogen fertilizers with different physical properties.
- Nitrogen fixation includes industrial (Haber–Bosch) and biological pathways.
Concept / Approach:Statements (a), (b), and (d) are established facts: yellow/white phosphorus is indeed shipped under water; apatite’s general formula is Ca10(PO4)6(F,Cl,OH); nitrogen fixation is the conversion of N2 into combined forms like NH3 or organic nitrogen. The questionable statement is about hygroscopicity: ammonium nitrate is markedly more hygroscopic than urea and can absorb moisture to form sticky or liquefied masses, whereas urea is hygroscopic but significantly less so.
Step-by-Step Solution:Evaluate each statement against standard references.Confirm (a), (b), (d) as correct.Identify (c) as incorrect because ammonium nitrate, not urea, is the more hygroscopic material.
Verification / Alternative check:Material safety data and fertilizer handbooks rank AN as highly hygroscopic and prone to caking; urea is moderate and can be granulated with conditioners to improve storage.
Why Other Options Are Wrong:
- (a) True: water immersion prevents ignition/oxidation.
- (b) True: formula represents fluorapatite/hydroxylapatite family.
- (d) True: definition covers biological and industrial fixation.
- (e) False because (c) is incorrect.
Common Pitfalls:Assuming all nitrogen fertilizers behave similarly in storage; overlooking the severe caking and moisture uptake issues with ammonium nitrate.
Final Answer:Urea is more hygroscopic than ammonium nitrate