Final answer:
An atom that is a noble gas with 4 energy levels is an atom of Krypton (Kr). It has 4 energy levels and is stable and unreactive.
Step-by-step explanation:
An atom that is a noble gas with 4 energy levels is an atom of Krypton (Kr). Krypton has an atomic number of 36, which means it has 36 protons and 36 electrons. It belongs to the noble gas group on the periodic table, which is Group 18. The noble gases have full outer energy levels, meaning they are stable and unreactive. Krypton has its 4th energy level filled with 8 electrons, making it a noble gas with 4 energy levels.
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