Question

the temporary hardness of water is caused by calcium and magnesium ---

a. bicarbonate

b. carbonate

c sulphate

d nitrate

Explanation:

Temporary hardness in water is due to the presence of calcium and magnesium bicarbonates. These bicarbonates decompose on heating to form carbonates that precipitate out, reducing the hardness. Carbonates, sulphates, and nitrates of calcium and magnesium contribute to permanent hardness or are not related to water - hardness in this context.

Answer:

A. bicarbonate