Which noble gas has the highest first ionization energy?
In noble gas helium has the highest first ionization energy.
This is beause smaller the size greater will be the force of attraction and thus required more energy to remove an electron from a helium atom.
As we move down the group the first ionization energy become smaller. The force of attraction of the positively charged nucleus for electrons decrease as the square of the distance between them increase.
Which noble gas has the highest first ionization energy