Hard water is softened by which of the following? Choose the correct answer from the options given below.

1.Aeration

2.Boiling

3.Limestone (lime)

4.Ozone generation

5.Ion exchange

A1, 2, 3 only

B2, 3, 5 only ✓ Correct

C2, 3, 4 only

D3, 4, 5 only

Correct answer: (B) 2, 3, 5 only

Explanation

Hard water is softened by boiling, by lime and by ion exchange.

Statement 2, boiling, removes temporary hardness by precipitating carbonates.

Statement 3, lime, removes hardness through the lime or Clark process.

Statement 5, ion exchange, swaps hardness-causing ions for sodium or hydrogen ions.

Statement 1, aeration, and Statement 4, ozone generation, treat gases and pathogens but do not soften water.

Temporary hardness goes on boiling while permanent hardness needs ion exchange.

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