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Difficulty: MediumChemistry in Daily Life and Industrial Applications

Consider the following statements regarding chemical fertilizers and their industrial applications in agriculture:

1. Urea (NH2CONH2\text{NH}_2\text{CONH}_2) has the highest nitrogen content (approximately 46%46\%) among all solid commercial nitrogenous fertilizers, supplying nitrogen in the amide form.
2. Single Superphosphate (SSP) is manufactured industrially by digesting ground rock phosphate with concentrated nitric acid.
3. Neem-coating of urea retards the activity of nitrifying bacteria in the soil, thereby decreasing nitrogen loss via leaching and volatilization.

Which of the statements given above are correct?

  1. A
    1 and 2 only
  2. 1 and 3 onlyAnswer
  3. C
    2 and 3 only
  4. D
    1, 2 and 3

Answer

Statements 1 and 3 only are correct.
The correct selection includes statements 1 and 3. Urea contains 46%46\% nitrogen by mass in amide form, representing the highest concentration among solid nitrogenous fertilizers. Neem coating provides natural triterpenoids that function as nitrification inhibitors, slowing the transformation of ammonium to nitrate and mitigating leaching and denitrification losses. The second statement is incorrect because Single Superphosphate is industrially manufactured using concentrated sulfuric acid rather than nitric acid.

Step-by-Step Solution

1
Evaluate the composition and nitrogen delivery mechanism of urea (Statement 1).
Urea (NH2CONH2\text{NH}_2\text{CONH}_2) has a molar mass of 60 g/mol60\text{ g/mol} with two nitrogen atoms contributing 28 g/mol28\text{ g/mol} (2860×100≈46.6%\frac{28}{60} \times 100 \approx 46.6\%). It delivers nitrogen in amide form which is converted to ammoniacal and nitrate forms in soil.
Confirming the exact chemical formulation and percentage composition validates the first statement.
2
Analyze the industrial synthesis of Single Superphosphate (Statement 2).
Single Superphosphate (SSP) is produced by reacting insoluble fluorapatite/rock phosphate (Ca3(PO4)2\text{Ca}_3(\text{PO}_4)_2) with concentrated sulfuric acid (H2SO4\text{H}_2\text{SO}_4) to form water-soluble monocalcium phosphate (Ca(H2PO4)2\text{Ca}(\text{H}_2\text{PO}_4)_2) and gypsum (CaSO4⋅2H2O\text{CaSO}_4\cdot2\text{H}_2\text{O}). Treatment with nitric acid produces nitrophosphate instead.
Identifying the specific mineral acid used in industrial phosphorus fertilizer manufacture shows the second statement is false.
3
Assess the chemical and biological function of neem-coated urea (Statement 3).
Neem oil contains bioactive triterpenoids that inhibit *Nitrosomonas* and *Nitrobacter* soil bacteria, slowing the oxidative conversion of ammonium into highly leachable nitrate.
Verifying the nitrification inhibition property confirms that the third statement is correct.

Key Concept

Chemical composition, industrial synthesis, and biochemical efficiency mechanisms of nitrogenous and phosphatic fertilizers.
Estimated Time:1m 15s
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Topics

Chemistry in Daily Life and Industrial Applications

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