What is $X$ in the following reaction?
$MgCl_2 + 2H_2O \to X + 2HCl + H_2O$

Given below are two statements: One is labelled as Assertion $A$ and the other labelled as Reason $R$.
Assertion $A$: During the boiling of water having temporary hardness,$Mg(HCO_3)_2$ is converted to $MgCO_3$.
Reason $R$: The solubility product of $Mg(OH)_2$ is greater than that of $MgCO_3$.
In the light of the above statements,choose the most appropriate answer from the options given below.

Calgon is

Temperature of maximum density of $H_2O$ is $y \ K$ and $D_2O$ is $x \ K$. $(x-y)$ (in $K$) is nearly

Which of the following properties is less for $D_2O$ than $H_2O$?

Lime or $CaCl_2$ is added to water to remove which of the following impurities?