Which electron removal from the valence shell in carbon atom requires the highest energy?
The correct option is D 4th electron
After removing the 1st electron, the energy required to remove the 2nd electron from its orbit is higher than that required to remove the 1st electron. This is because 6 protons now attract only 5 electrons and they exert more force on them compared to the previous case.
Similarly, energy to remove the 4th electron >>> energy to remove the 3rd electron >> energy to remove the 2nd electron.