Urea is a widely used nitrogenous fertilizer. Its nitrogen content by mass is approximately:
A. 35%
B. 46%
C. 82%
D. 21%
Answer: Option B
Solution (By JKSSB Mock Tests)
Urea, CO(NH₂)₂, molar mass = 60 g/mol. Mass of N = 2×14 = 28 g. Percentage N = (28/60) × 100 ≈ 46.67%, commonly rounded to 46%. It has the highest nitrogen content among solid fertilizers, making it economical. DAP (diammonium phosphate) has 18% N and 46% P₂O₅. Ammonium nitrate has 33% N. Urea is converted to ammonia and carbon dioxide by soil urease enzyme.
Explanation:
Ozone (O₃) has a coordinate bond (dative bond). One oxygen atom donates a lone pair to another oxygen atom. The Lewis structure shows O=O⁺–O⁻ or resonance. NaCl is ionic; H₂O has polar covalent bonds; NH₃ has ordinary covalent bonds (though it can donate a lone pair to form coordinate bond in NH₄⁺).
Explanation:
Natural gas (methane) is often found above petroleum deposits, trapped under cap rock. It burns cleaner than coal and oil, producing less CO₂, no SO₂, and minimal particulates. Coal (including lignite) contains more impurities. Peat is an early stage of coal. Natural gas is transported via pipelines or as LNG.
Explanation:
Rhizobium is a nitrogen-fixing bacterium that lives in root nodules of legumes and converts atmospheric N₂ to ammonia, enriching soil fertility naturally. It is a biofertilizer. Urea and ammonium sulfate are synthetic nitrogenous fertilizers. Superphosphate is a synthetic phosphorus fertilizer. Biofertilizers like Azotobacter, Blue-green algae, and mycorrhizae are eco-friendly and sustainable.
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