Energy required to remove e– from singly ionized helium atom =
(13.6)Z2
12
=54.4eV(∵Z=2) Energy required to remove e− from helium atom =xeV According to question, 54.4eV=2.2x⇒x=24.73eV Therefore, energy required to ionize helium atom =(54.4+24.73)eV=79.12eV