Among KO2, KAlO2, CaO2 and NO2^+, unpaired electron is present in : — Chemical Bonding Chemistry Question

💡 Solution & Explanation

Step 1: Identify the ionic constituents of each compound: KO2 is composed of K^+ and the superoxide ion O2^-; KAlO2 is composed of K^+, Al^3+, and the meta-aluminate ion AlO2^-; CaO2 is composed of Ca^2+ and the peroxide ion O2^2-. Step 2: Determine the electronic structures of the anions/cations. Peroxide (O2^2-) has 18 electrons (all paired). AlO2^- and NO2^+ are even-electron closed-shell species (all paired). Step 3: Superoxide (O2^-) has 17 valence electrons, with an odd number of electrons and one unpaired electron in its antibonding pi* molecular orbital. Thus, an unpaired electron is present only in KO2, matching option (c).