Water has higher thermal conductivity, specific heat. dielectric constant and surface tension in comparison to other liquids.

$$\eqalign{ & MnO_4^ - + 5{e^ - } \to M{n^{2 + }}\,\,{\text{(acidic)}} \cr & MnO_4^ - + 3{e^ - } \to Mn{O_2}\,{\text{(basic)}} \cr & 100\,mL\,{H_2}{O_2} \equiv 100 \times 5N \cr & MnO_4^ - \equiv V \times 3N\,Mn{O_2} \cr & N = \frac{{500}}{3}mL \cr} $$

Deuterium is $$_1^2H.$$

$${D_2}O$$  actually has higher freezing point $$\left( {{{3.8}^ \circ }C} \right)$$  than water $${H_2}O\left( {{0^ \circ }C} \right)$$

Hydrogen forms a diatomic molecule similar to halogens but alkali metals are monoatomic.

$${D_2}O$$  has higher freezing point than that of water.

$$\eqalign{ & KI{O_4} + {H_2}{O_2} \to KI{O_3} + {H_2}O + {O_2} \cr & {\text{Thus}}\,{H_2}{O_2}\,{\text{is}}\,{\text{acting}}\,{\text{as}}\,{\text{a}}\,{\text{reducing}}\,{\text{agent}} \cr & 2N{H_2}OH + {H_2}{O_2} \to {N_2} + 4{H_2}O \cr & {\text{Here}}\,{H_2}{O_2}\,{\text{is}}\,{\text{acting}}\,{\text{as}}\,{\text{an}}\,{\text{oxidising}}\,{\text{agent}} \cr} $$

The metals of group 7, 8 and 9 do not form hydrides.

$$H - 1{s^1};He - 1{s^2}$$
Halogen, $$X - n{s^2}n{p^5};$$   Inert gas $$ - n{s^2}n{p^6}$$
Both have one electron less than the nearest noble gas configuration.

Bosch process is used to prepare di-hydrogen commercially. In this process water gas prepared from coal & water at $$1270\,K$$  is mixed with two times its volume of steam passed over $$F{e_2}{O_3}$$  in presence of promoter $$C{r_2}{O_3}.$$