Hydrolysis of which of the following is not an example of a redox reaction?

Which of the following noble gases exhibits higher oxidation states?

Given below are two statements:
Statement-$I$: Noble gases have very high boiling points.
Statement-$II$: Noble gases are monoatomic gases. They are held together by strong dispersion forces. Because of this,they are liquefied at very low temperatures. Hence,they have very high boiling points.
In the light of the above statements,choose the correct answer from the options given below:

Which statements among the following are correct about Helium?
$(i)$ Liquid helium is used to sustain powerful superconducting magnets.
$(ii)$ Liquid helium is useful to carry low temperature experiments.
$(iii)$ It is a heavy gas.
$(iv)$ It is a flammable gas.

Which of the following does not exist?

Complete hydrolysis of $XeF_6$ gives $HF$ along with compound $X$. The hybridisation in $X$ is