Which of the following substances cause permanent hardness of water

What causes permanent hardness of water ?

Some substances when dissolved in water cause hardness of water. Which of the following substances cause hardness of water? Sodium chloride, Calcium bicarbonate, Calcium carbonate, Calcium sulphate, Magnesium sulphate, Calcium chloride, Magnesium carbonate

Permanent hardness of water is due to

By adding which of the following process, permanent hardness of water can be removed.

By adding which of the following process, permanent hardness of water can be removed.

The cause of permanent hardness of water is due to

Which of the following is used for removing permanent hardness of water?