Multiple choice general knowledge science & technology

Alums are useful for a range of industrial processes. They are soluble in water; have an astringent, acid, and sweetish taste. The chemical formula for Alum is -

  1. KAl(SO4)4.8H2O

  2. KAl(SO4)2.10H2O

  3. KAl(SO4)3.10H2O

  4. KAl(SO4)2.12H2O
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D Correct answer
Explanation

Alum has the general formula M2SO4·M2(SO4)3·24H2O, but potassium alum (the most common type) is KAl(SO4)2·12H2O - potassium aluminum sulfate dodecahydrate. The 12 water molecules of hydration are characteristic of crystalline alum structure.

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