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Po is a radioactive element.It has the 84 atomic number.
Po has 84 protons because the atomic number is 84, and the number of protons is the same as the atomic number.
krypton's atomic number is rounded to 84
Polonium has 84 protons and electrons; the number of neutrons is different for each isotope:
Number of neutrons = Atomic mass of an isotope - Atomic number of polonium (84)
84 protons in polonium, as its atomic number is 84