Which of the following is not obtained by the direct reaction of constituent elements?

Which of the following is employed in flash tubes in photography?

The number of peroxide bonds in the perxenate ion $[XeO_6]^{4-}$ is ........

$XeF_6$ on partial hydrolysis with water produces a compound '$X$'. The same compound '$X$' is formed when $XeF_6$ reacts with silica. The compound '$X$' is

Fluorine forms chemical compounds with

$0.1 \ mol$ of $XeF_6$ is treated with $1.8 \ g$ of water. The product obtained is