Which method is used to obtain completely demineralized water?
A. Filtration
B. Sedimentation
C. Distillation
D. Ion-exchange process
Answer: Option D
Solution (By JKSSB Mock Tests)
The ion-exchange process (using cation and anion exchange resins) removes all dissolved cations and anions from water, producing completely demineralized (deionized) water. Distillation removes most impurities but may still contain trace dissolved gases or volatile organics.
Explanation:
Hydrogen has the highest calorific value (~150 kJ/g or 141.9 MJ/kg) because it has no heavier atoms like carbon and its combustion produces water, a very stable product. Methane ~55.5 kJ/g, coal ~25-35 kJ/g, wood ~17 kJ/g. Hydrogen is a clean fuel, but storage and production challenges remain. It can be used in fuel cells or internal combustion engines.
Explanation:
Baking soda is sodium hydrogen carbonate (NaHCO₃). It is used as a leavening agent in baking (produces CO₂ upon heating or with acid), as an antacid, and in fire extinguishers. Sodium carbonate (Na₂CO₃) is washing soda. Calcium carbonate is limestone/marble. Potassium carbonate is potash. Baking powder is a mixture of NaHCO₃ and a weak acid like tartaric acid.
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