Hydrogen can be obtained from water,by the action of water on

Hydrogen does not combine with

Consider the reactions:
$I$. $CO + 3 H_2 \xrightarrow{A} CH_4 + H_2 O$
$II$. $CO + 2 H_2 \xrightarrow{B} CH_3 OH$
$III$. $O_2 + 2 H_2 \xrightarrow{C} 2 H_2 O$
The catalysts $A, B, C$ are respectively:

Saline hydrides are known to react with water violently producing fire. Can $CO_2$,a well-known fire extinguisher,be used in this case? Explain.

In an ice crystal,each water molecule is hydrogen bonded to $.......$ neighbouring molecules.

Elements of which of the following group$(s)$ of the periodic table do not form hydrides?