How can `D_(2)O_(2)` prepared from water ? Mention the physical properties in which `D_(2)O` differs from `H_(2)O`. Given at least three reaction of `D_(2)O` showing the exchange of hydrogen with deuterium.

Explanation

(i)`D_(2)O` can be prepare by prolonged electrociysis of water.
(ii) Physical properties
(a) `D_(2)O` is colourless, odourless, tasteless liquid. It has maximum density `- 1.1073 g mL^(-1) ` at `11.6^(@)C`. (Maximum density of water at `45^(@)C`)
(b) Solubility of salts in heavy water is less than in ordinary water because it is more viscous than ordinary water.
(c) Nearly, all physical constants of `D_(2)O` are higher than `H_(2)O` .It is due to the greater nuclear mass of decuterium atom than H-atom and stronger H-bonding in `D_(2)O` than `H_(2)O`.
(iii) Exchange reactions of hydrogen with deuterium
`NaOH + D_(2) O to NaOD + HOD`
`HCl + D_(2)O to DCl + HOD`
`NH_(4)Cl + D_(2)O to NH_(3)DCL + HOD`