Question

Which one of the following impurities present in colloidal solution cannot be removed by electrodialysis?
(a) Sodium chloride
(b) Potassium sulphate
(c) Urea
(d) Calcium chloride

Answer 1

urea because it dissolved in the medium

Answer 2

(c) Urea present in colloidal solution cannot be removed by Electrodialysis.

Explanation of the answer:

• Electrodialysis refers to the technique of removal of electrolytic impurities.
• It involves the movement of ions towards the oppositely charged electrodes.
• Urea being a covalent compound does not dissociate to provide ions.
• Thus, urea is a non-electrolyte hence it cannot be removed by Electrodialysis.
• Hence, the correct answer among all the options is option (c) Urea.

Explanation for the incorrect options:

• All the other given compounds: Sodium chloride; Potassium sulphate and Calcium chloride are ionic so, they can undergo dissociation to provide oppositely charged ions and therefore can be separated.

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