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COMEDK · Chemistry · 3. Classification of Elements and Periodicity in Properties

Which of the following species has lowest ionisation enthalpy?

  1. A Q
  2. B \(\mathrm{O}_2\)
  3. C \(\mathrm{O}_2^{+}\)
  4. D \(\mathrm{O}_2^{-}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\mathrm{O}_2^{-}\)

Step-by-step Solution

Detailed explanation

During addition of electron to \(\mathrm{O}_2\) to form \(\mathrm{O}_2^{-}\), the additional \(\pi\)-molecular electron is added to the less stable antibonding orbital. Therefore, it is easier to remove an electron from \(\mathrm{O}_2^{-}\) ion to form a neutral \(\mathrm{O}_2\)…