Which water treatment method eliminates both temporary and permanent hardness ?
Show answer Hide answer
Answer: C. Distillation
Explanation
Distillation vaporizes water and leaves behind all dissolved mineral salts, eliminating all hardness. Thermal distillation separates pure water vapor from mineral impurities completely and reliably. Both temporary hardness and permanent hardness are removed through the phase change of distillation. Water hardness is caused by dissolved calcium and magnesium bicarbonate, sulfate, and chloride salts. Distillation involves boiling liquid water followed by condensing the resulting pure steam. Non-volatile minerals cannot escape the boiling chamber during standard distillation processes.
Distilled water is essential for laboratory experiments, medical equipment, and industrial boilers. While effective, distillation requires significant energy input compared to chemical softening methods. Hard water scaling can severely damage industrial heat exchangers and heating appliances. Option A removes suspended solids but leaves dissolved hardness minerals in the water. Option B boiling only precipitates temporary hardness carbonates and fails to remove permanent hardness. Option D is incorrect because distillation successfully eliminates both types of water hardness.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. What is the primary solute in the mother liquor generated by the salt industry ?
Show answer Hide answer
Answer: D. Bromine
The remaining bittern liquor left after salt crystallization is a rich commercial source of bromine. Bromine is extracted from concentrated mother liquors produced during industrial seawater processing. Seawater bittern...
Q2. Which product is not manufactured commercially from seawater ?
Show answer Hide answer
Answer: D. Iodine
Iodine is extracted commercially from seaweed or underground brines rather than from raw seawater. Direct extraction from seawater is economically unfeasible due to the extremely low iodine concentration. Industrial prod...
Q3. Which paper variety is produced without requiring filler materials ?
Show answer Hide answer
Answer: C. Blotting paper
Blotting paper is made to be highly absorbent, so mineral filler materials are omitted. Omitting fillers prevents mineral particles from blocking the microscopic capillary spaces inside paper. High porosity and absorbenc...
Q4. Which compound is unlikely to be found in vegetable oils ?
Show answer Hide answer
Answer: A. Citric acid
Vegetable oils are triglycerides composed of glycerol and fatty acids, excluding citric acid. Citric acid is a water-soluble tricarboxylic acid not found in natural triglyceride structures. Fatty acid chains like oleic a...
Q5. What constitutes the most significant drawback discouraging the choice of mercury cells for caustic soda production ?
Show answer Hide answer
Answer: D. Pollution of water stream by mercury
Mercury cell technology causes severe environmental pollution when toxic mercury enters wastewater streams. This significant ecological drawback led to strict global regulations restricting mercury cell usage. Preventing...
Q6. Which oil is preferred for formulating paints ?
Show answer Hide answer
Answer: A. Drying oil
Drying oils contain polyunsaturated fatty acids that undergo oxidation and polymerization when exposed. Exposure to atmospheric oxygen causes drying oils to crosslink into a solid protective film. The chemical curing pro...