Which of the following elements has zero valency?

The structure of $XeOF_4$ is

Noble gases have very low boiling points. Why?

The inert gases are

$XeF_4 + O_2F_2 \rightarrow X + O_2$
$X + H_2O$ $(1 \ mole)$ $\rightarrow Y + 2 HF$
The shapes of molecules of $X$ and $Y$ respectively are:

The reason for not storing $XeF_6$ in a glass or a quartz vessel is that