Answer:
3.46*10⁻²² kJ
Explanation:
By the Avogadro's number, 1 mole of electrons at 1 mole of atoms correspond to 6.02x10²³ electrons. So it's necessary 208.4 kJ to remove 6.02x10²³ electrons. To remove a single electron:
6.02*10²³ electrons ---------------- 208.4 kJ
1 electron ---------------- x
By a simple direct three rule:
6.02*10²³ x = 208.4
x = 3.46*10⁻²² kJ