Chemistry - Environmental Chemistry Question with Solution | TestHub

ChemistryEnvironmental ChemistryWater PollutionMedium2 minQB
ChemistryMediumsingle choice
Passage / Comprehension

The hardness of natural water is generally caused by presence of bicarbonates, chlorides and sulphates of calcium and magnesium but infact soluble salts that form a scum with soap cause hardness. Hardness of water is two types : (1) temporary hardness. (2) permanent hardness.

Permanent hardness is removed by -

Options:

Answer:
D
Solution:

Permanent hardness is caused by chlorides and sulfates of calcium and magnesium (CaCl₂, MgCl₂, CaSO₄, MgSO₄).

It cannot be removed by boiling.

It is removed by adding sodium carbonate (Na₂CO₃), which precipitates calcium and magnesium as carbonates.

Reaction:

Hence, permanent hardness is removed by:

Stream:JEESubject:ChemistryTopic:Environmental ChemistrySubtopic:Water Pollution
2mℹ️ Source: QB

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