Why are the elements of Group 18 known as noble gases ?

Explanation

The elements present in group `18` have their valence shelf orbatin comlentely filled and therefore react with a few element only under certain condition .Therefore , they qare known as nible gases.
(b) Noble gases being monocatemic have no interatonic forces except weak displersion forces and therefore they are liquefied at very low temperature .Hence they have low holding points.
(c ) No, the produces of hydrogen are `XaOF_(4) and XeO_(2)F_(2)` where the oxidetaion state of all the elements remain the same as it was in the reacting state.
`overset(+6)(XeF_(6)) + H_(2)O to overset(+6)(XeOF_(4)) + 2HF`
`overset(+6)(XeF_(6)) + 2H_(2)O to overset(+6)(XeO_(2)F_(4)) + 4HF`