Temporary hardness in water is also known as:

Correct option is D

Temporary hardness in water is primarily caused by the presence of bicarbonates of calcium and magnesium (Ca(HCO₃)₂ and Mg(HCO₃)₂). When water containing these bicarbonates is boiled, the bicarbonates decompose to form insoluble carbonates, which precipitate out, removing the hardness. This type of hardness is called "temporary hardness" because it can be removed by simple boiling.
Information Booster: · Temporary hardness is caused by calcium and magnesium bicarbonates.
· Boiling water is an effective method to remove temporary hardness.
· Temporary hardness is different from permanent hardness, which requires chemical treatment to remove.
Additional Knowledge: (a) Sulphate hardness: · Permanent hardness caused by calcium sulphate (CaSO₄) and magnesium sulphate (MgSO₄).
· It cannot be removed by boiling; requires chemical treatment like ion exchange or addition of washing soda.
(b) Nitrate hardness: · Rarely causes significant hardness in water.
· Associated with high nitrate levels, often due to agricultural runoff.
· Excess nitrate in water poses health risks, particularly for infants (blue baby syndrome).
(c) Chloride hardness: · Permanent hardness due to calcium chloride (CaCl₂) and magnesium chloride (MgCl₂).
· Similar to sulphates, it remains in solution even after boiling.