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Difficulty: MediumChemistry in Daily Life and Industrial Applications

Chemical substances are extensively utilized in water purification, industrial refrigeration, and safety equipment. Which of the following statements regarding the applications and behaviors of these chemical compounds are correct?

  1. Bleaching powder (CaOCl2\text{CaOCl}_2) acts as an effective disinfectant in municipal water treatment through the liberation of available chlorine.Answer
  2. B
    Potash alum softens hard water primarily by functioning as an ion-exchange resin to remove dissolved magnesium and calcium sulfates.
  3. Solid carbon dioxide (CO2\text{CO}_2), known as dry ice, sublimes directly from solid to gas at atmospheric pressure, making it a coolant that leaves no liquid residue.Answer
  4. D
    Carbon monoxide gas is commonly charged into portable fire extinguishers because of its non-flammable nature and flame-blanketing property.

Answer

The statements confirming that bleaching powder acts as a disinfectant through the release of active chlorine and that solid carbon dioxide functions as a residue-free coolant via sublimation are correct.
Bleaching powder serves as an established germicidal disinfectant by generating active hypochlorite and chlorine species in aqueous solution, while solid carbon dioxide (dry ice) sublimes cleanly into vapor under standard conditions, providing cryogenic cooling without liquid byproduct.

Step-by-Step Solution

1
Evaluate the mechanism of bleaching powder in water treatment
Bleaching powder (CaOCl2\text{CaOCl}_2) reacts in water to release active chlorine, which oxidizes organic matter and sterilizes water supplies.
Chlorine chemistry is fundamental to municipal disinfection protocols.
2
Examine the role of potash alum versus water softening methods
Potash alum (K2SO4⋅Al2(SO4)3⋅24H2O\text{K}_2\text{SO}_4\cdot\text{Al}_2(\text{SO}_4)_3\cdot 24\text{H}_2\text{O}) provides Al3+\text{Al}^{3+} cations that destabilize colloidal suspensions (coagulation/flocculation), but it does not remove dissolved permanent hardness ions like zeolites or ion-exchange resins do.
Distinguishing water clarification from chemical softening prevents functional misattribution.
3
Assess the physical behavior and utility of dry ice
Solid CO2\text{CO}_2 undergoes direct sublimation into gaseous carbon dioxide at atmospheric pressure without melting, preserving packaging integrity during perishable transport.
Thermodynamic phase change properties determine its industrial refrigeration use.
4
Analyze the gas composition in fire extinguishing equipment
Carbon monoxide (CO\text{CO}) is a toxic, flammable gas (2CO+O2→2CO2\text{2CO} + \text{O}_2 \rightarrow \text{2CO}_2) and cannot suppress fires; carbon dioxide (CO2\text{CO}_2) or dry chemical agents are used instead.
Safety compounds must be non-combustible and non-toxic during deployment.

Key Concept

Chemical principles and industrial applications of disinfectants, coagulants, sublimating refrigerants, and non-combustible gases
Estimated Time:1m 0s
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Topics

Chemistry in Daily Life and Industrial Applications

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