Question

What number of unpaired electrons are there in Xe atom?

Answer 1

Zero.

Explanation:

We can start by writing the electron configuration of xenon, `Xe`, with reference to the Aufbau ("build-up") principle:

A neutral xenon atom has 54 electrons and would have the electron configuration
`1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^10 5p^6`.

An electron is considered "unpaired" if it occupies a single atomic electron orbital with the other half of the orbital left unoccupied- possible only if the orbital is incomplete.

Each `s` orbital holds a maximum of two electrons, each `p` six electrons, and each `d` ten electrons. As seen from the electron configuration, all electron orbitals occupied in a ground-state xenon atom are filled to their maximum capacity, leaving no half-filled orbitals that might host unpaired electrons.

Also, this fact is consistent with the observation that as a noble gas, xenon exists as a monoatomic gas at room temperature and is highly inert (chemically speaking). None of which are characteristic of a radical- an atom that has unpaired electrons.

Sources:
https://en.wikipedia.org/wiki/Xenon

https://en.wikipedia.org/wiki/Unpaired_electron