Question Detail
Question
Which of the following elements has the highest first ionization energy?
Correct Answer
Option C is the correct answer.
Detailed Explanation
Ionization energy generally increases across a period and decreases down a group. Helium, being at the top right of the periodic table (excluding noble gases), has a very stable full electron shell and the highest first ionization energy of all elements.
Hint
Elements with full valence shells, especially small ones, are very hard to ionize.