Which one of the following methods is most suitable for preparing deionized water?

Describe the structure of the common form of ice.

Knowing the properties of $H_2O$ and $D_2O$,do you think that $D_2O$ can be used for drinking purposes?

Write two reactions to explain the amphoteric nature of water.

Melting point,enthalpy of vaporisation and viscosity data of $H_2O$ and $D_2O$ is given below.

$Property$	$H_2O$ vs $D_2O$
$Melting$ $point/K$	$273.0$ vs $276.8$
$Enthalpy$ $of$ $vaporisation$ $at$ $(373 \ K) / kJ \ mol^{-1}$	$40.66$ vs $41.61$
$Viscosity/centipoise$	$0.8903$ vs $1.107$

On the basis of this data,explain in which of these liquids intermolecular forces are stronger?

Statements about heavy water are given below.
$A.$ Heavy water is used in exchange reactions for the study of reaction mechanisms.
$B.$ Heavy water is prepared by exhaustive electrolysis of water.
$C.$ Heavy water has higher boiling point than ordinary water.
$D.$ Viscosity of $H_2O$ is greater than $D_2O$.