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MolSynapse / Question bank / p-Block Elements: Groups 13 and 14 / Aluminium compounds and alums

NEET levelSingle correct optionDifficulty 1 of 3pb131

Alum is used for purification of water because it

Akills bacteria by releasing chlorine
Bremoves temporary hardness by precipitating carbonates
Craises the pH of water strongly
Dcoagulates suspended colloidal impurities

Answer: D

Al X^{3 +}

from alum neutralises the charge of negatively charged colloidal particles and coagulates them as

Al (OH) X_{3}

floc, which settles out.

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