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Why do we add alum to purify water ?...

Why do we add alum to purify water ?

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We add alum to purify water as alum coagulates the colloidal impurities present in water, so that these impurities get settle down and remove by decantation or filtration. Thus, water gets purified by adding alum to water.
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NCERT EXEMPLAR ENGLISH-SURFACE CHEMISTRY-Short Answer Type Qrestions
  1. Gelatin which is a peptide is added in ice-creams. What can be its ro...

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  2. What is collodion?

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  3. Why do we add alum to purify water ?

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  4. Which phenomenon occurs when an electric field is applied to a colloid...

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  5. What causes Brownian motion in colloidal dispersion?

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  6. A colloid is formed by adding FeCl(3) in excess of hot water. What wil...

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  7. How do emulsifiers stabilise emulsion ? Name two emulsifiers.

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  8. Why are some medicines more effective in the colloidal form?

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  9. Why does leather get hardened after tanning?

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  10. How does the precipitation of colloidal smoke take place in Cottrell p...

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  11. How will you distiguish between dispersed phase and dispersion medium ...

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  12. On the basis of Hardy-schulze rule explain why the coagulating power o...

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  13. Why does bleeding stop by rubbing moist alum?

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  14. Why is Fe(OH)(3) colloid positively charged when prepared by adding Fe...

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  15. Why do physisorption and chermisorption behave differently with rise i...

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  16. What happens when dialysis is prolonged?

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  17. Why does the white precipitate of silver halide become coloured in the...

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  18. What is the role of activated charcoal in gas mask used in coal mines?

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  19. How does a delta form at the meeting place of sea and river water?

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  20. Given an example where physisorption changes to chemisorption with ris...

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