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प्रश्न
Why do we add alum to purify water?
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उत्तर
River water carries negatively charged colloidal particles of clay and sand; alum \[\ce{(K2SO4Al2(SO4)3 24H2O)}\] is added to river water to coagulate the colloidal particles of clay and sand. Thus, alum helps to purify water.
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संबंधित प्रश्न
What is the reason for the stability of colloidal sols?
Define the following terms: Associated colloids
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Define the following term : Brownian movement
A colloidal sol is prepared by the given method in the figure. What is the charge on hydrated ferric oxide colloidal particles formed in the test tube? How is the solution represented?

A colloidal sol is prepared by the given method in the figure. What is the charge on hydrated ferric oxide colloidal particles formed in the test tube? How is the sol represented?

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(i) Lyophobic sol is protected.
(ii) Lyophilic sol is protected.
(iii) Film of lyophilic sol is formed over lyophobic sol.
(iv) Film of lyophobic sol is formed over lyophilic sol.
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(i) Reverse osmosis takes place.
(ii) Electroosmosis takes place.
(iii) Dispersion medium begins to move.
(iv) Dispersion medium becomes stationary.
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Reason: Pore size of the filter paper becomes more than the size of colloidal particle.
Give reason for the following:
Lyophilic colloidal solutions are more stable than lyophobic colloidal solutions.
Which of the following is used for removing change on colloidal solution?
State the Hardy-Schulze rule.
What is electrophoresis?
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