When temporary hard water containing $Mg(HCO_3)_2$ is boiled,the precipitate formed is of:

Assertion $(A)$ : $NaCl$ is less soluble in heavy water than in ordinary water.
Reason $(R)$ : Dielectric constant of ordinary water is more than that of heavy water.
The correct answer is

Describe the methods to remove the permanent hardness of water.

Which of the following can effectively remove all types of hardness of water?

The products obtained during the treatment of hard water using Clark's method are:

$A$ substance used as a moderator in nuclear reactors is