Import Question JSON

$\text{HINT: S}^- \text{ has maximum ionization energy.}$ $\text{Explanation:}$ $\text{The energy ionization needed to remove an electron from a neutral atom is called ionization energy.}$ $\text{The more close the outermost electrons to the nucleus, the more it will become difficult to remove an electron from the outermost shell.}$ $\text{The outermost electrons in Se}^-, \text{Te}^-, \text{S}^- \text{ and O}^- \text{is present in electrons in 4p, 5p, 3p and 2p orbitals respectively.}$ $\text{The expected order of decreasing ionization energy is,}$ $\text{O}^- > \text{S}^- > \text{Se}^- > \text{Te}^-$ $\text{but, the actual order of decreasing ionization energy is,}$ $\text{S}^- > \text{O}^- > \text{Se}^- > \text{Te}^-$ $\text{This is because the 2p orbital has a smaller size and the inter electronic repulsion in compact 2p- orbitals is more than the 3p- orbitals.}$ $\text{Thus, the electron present in the outermost shell of the oxygen anion feels more repulsion in 2p- orbital than the electron present in the 3p-orbital of sulfur anion, so it becomes easy to remove an electron from the outermost shell of oxygen.}$ $\text{Therefore, S}^- \text{ has maximum ionization energy.}$ $\text{So, option 2 is the correct answer.}$