Question

Which of the following sets are not correctly matched?
I) O\textsubscript{2}\textsuperscript{+}, O\textsubscript{2}\textsuperscript{–} \hspace{1em} – diamagnetic
II) O\textsubscript{2}\textsuperscript{–}, O\textsubscript{2} \hspace{3.8em} – paramagnetic
III) O\textsubscript{2}\textsuperscript{–}, O\textsubscript{2}\textsuperscript{2–} \hspace{1em} – diamagnetic
IV) O\textsubscript{2}\textsuperscript{+}, O\textsubscript{2}\textsuperscript{2–} \hspace{1em} – paramagnetic

• A. II& III
• B. I& II
• C. III& IV
• D. I& III

Hint:

Use the molecular orbital diagram to determine magnetic properties: unpaired electrons → paramagnetic, all paired → diamagnetic.

Answer 1

The Correct Option is C

- O\textsubscript{2}\textsuperscript{–} (15 electrons) is **paramagnetic**, not diamagnetic. - O\textsubscript{2}\textsuperscript{2–} (16 electrons) is **diamagnetic** - O\textsubscript{2}\textsuperscript{+} (15 electrons) is **paramagnetic** Thus: - III (claims O\textsubscript{2}\textsuperscript{–} is diamagnetic) is incorrect. - IV (claims both are paramagnetic, but O\textsubscript{2}\textsuperscript{2–} is diamagnetic) is also incorrect.