Question:
The total number of species from the following in which one unpaired electron is present, is _________.
N2, O2, C2−, O2−, O22−, H2+, CN−, He2+
Correct Answer: 4
Species having one unpaired electron show paramagnetic behaviour.
• N₂: All electrons paired → Diamagnetic
• O₂: Two unpaired electrons → Not counted
• C₂⁻: One unpaired electron → Counted
• O₂⁻: One unpaired electron → Counted
• O₂²⁻: All electrons paired → Diamagnetic
• H₂⁺: One electron → Unpaired → Counted
• CN⁻: All electrons paired → Diamagnetic
• He₂⁺: One unpaired electron → Counted
Total species having exactly one unpaired electron = 4