Which of the following represents a double displacement reaction?
A. Zn + CuSO₄ → ZnSO₄ + Cu
B. AgNO₃ + NaCl → AgCl↓ + NaNO₃
C. 2Mg + O₂ → 2MgO
D. CaCO₃ → CaO + CO₂
Answer: Option B
Solution (By JKSSB Mock Tests)
AgNO₃ + NaCl → AgCl↓ + NaNO₃ is a double displacement (precipitation) reaction where ions exchange partners. Ag⁺ pairs with Cl⁻ to form a white precipitate of AgCl, and Na⁺ remains with NO₃⁻. Option A is combination, B is single displacement, D is decomposition. Double displacement generally forms a precipitate, gas, or water. Neutralization is also a double displacement: HCl + NaOH → NaCl + H₂O.
Explanation:
Urea is chemically carbamide, with the formula CO(NH₂)₂. It is synthesized from ammonia and carbon dioxide in the Bosch-Meiser process. Option A is ammonium nitrate, B is ammonium sulfate, and D is calcium dihydrogen phosphate (a component of single superphosphate).
Explanation:
Minamata disease is a neurological syndrome caused by severe mercury poisoning. It was first discovered in Minamata city, Japan, due to the release of methylmercury in industrial wastewater from a chemical factory, which bioaccumulated in fish and shellfish consumed by the local population.
Explanation:
Detergents with branched hydrocarbon chains (ABS) resist bacterial degradation and persist in water bodies causing foam and pollution. Linear alkylbenzene sulfonates (LAS) are biodegradable and preferred. Soap is biodegradable but forms scum with hard water. Sodium lauryl sulfate is used in shampoos and is biodegradable. Environmental regulations now mandate the use of linear chain detergents.
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