Which element out of the He, Ar, Kr and Xe forms least number of compounds ?

Which element out of the following He, Ar, Kr and Xe forms least number of compounds ?

Why Xe forms more compounds than Kr?

Why Xe forms more compounds than Kr?

Which element among inert gases form, maximum number of compounds? Write the formula of one of the compounds formed by the element.

Which out of He, Ne, Ar, Kr and Xe can be easily liquefied? Why?

The element which forms maximum number of compound is

Which element forms the highest number of compounds in the periodic table ?

Why He, Ne and Ar do not form compounds while Xe does?