Which of the following does not exist?

The correct order of enthalpy of vaporisation of noble gases is

Who among the following first prepared a stable compound of a noble gas?

Which of the following is primarily contained in the colored discharge tubes used for advertising?

Match List-$I$ with List-$II$ and select the correct answer using the codes given below the lists:

List-$I$	List-$II$
$(A) \ XeF_4$	$(1) \ \text{Distorted octahedral}$
$(B) \ XeF_6$	$(2) \ \text{Tetrahedral}$
$(C) \ XeO_3$	$(3) \ \text{Square planar}$
$(D) \ XeO_4$	$(4) \ \text{Pyramidal}$

$Xe_{(g)}$ and $F_{2(g)}$ react in the ratio $1:20$ at $573 \ K$ and $60-70 \ bar$ to form $A$. When $A$ is completely hydrolyzed,$B$ and $HF$ are formed. $A$ and $B$ are respectively: