Which of the following elements is the most reactive?

Balance the following equation: $XeF_{6} + H_{2}O \rightarrow XeO_{2}F_{2} + HF$

Which of the following gases exists more abundantly in nature than the others?

The structure of the noble gas compound $XeF_4$ is

The hybridisation and structure of $XeF_6$ is :

Assertion $(A)$: Helium has the lowest boiling point $(4.2 \ K)$.
Reason $(R)$: The forces that exist between helium atoms are weak dispersion forces.