Which of the following is an example of a strong base?
A. NH₄OH
B. NaOH
C. Ca(OH)₂ (slightly soluble)
D. Mg(OH)₂
Answer: Option B
Solution (By JKExamLibrary)
NaOH is a strong base, fully dissociating into Na⁺ and OH⁻ ions. NH₄OH is a weak base. Ca(OH)₂ and Mg(OH)₂ are sparingly soluble but are considered strong bases in terms of dissociation of dissolved portion, but NaOH is the strongest among common ones.
Explanation:
Nitric acid (HNO3) is historically known as Aqua Fortis, which translates to 'strong water' in Latin. This name was given by early alchemists due to its ability to dissolve almost all metals, including silver, which was not dissolved by other known acids at the time.
Explanation:
Immiscible liquids (e.g., oil and water) form separate layers. A separating funnel is used to draw off the denser liquid from the bottom. Distillation methods are used for miscible liquids. Centrifugation separates solids from liquids or liquids of different densities in a mixture but not for two immiscible liquids efficiently in a lab; a separating funnel is simpler.
Explanation:
Soap (sodium/potassium salts of long-chain fatty acids) reacts with Ca²⁺ and Mg²⁺ ions in hard water to form insoluble calcium/magnesium salts (scum), which precipitates and does not lather. This wastes soap. Reaction: 2RCOONa + Ca²⁺ → (RCOO)₂Ca↓ + 2Na⁺. Detergents do not form scum because their calcium salts are soluble. Hardness is measured in ppm of CaCO₃.
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