Question

Which one will have the highest 2nd ionization energy
1s²2s²2p²3s¹
1s²2s²2p⁴
1s²2s²2p⁶
1s²2s²sp⁶3s²​

Answer 1

Answer:

I think its the second option

REASON

1) After 1st ionisation it is in half filled stage but a doubt may arise about the 4th option as it too will become half filled but observe how close the both are to the nucleus.In case of 4th it is far from nucleus and experiences comparatively less nuclear attraction(i.e we are talking about screening effect here).Therefor 2nd one will be your answer.