Verified Solution • 2025–26 Session moderate

QJEEM22Ch817a: JEE Main 2022 Chemistry - Class 11 JEEM22Ch817a Solution: Correct statement about alkali metal oxides is :

Correct statement about alkali metal oxides is :

Multiple Choice Options

  • A peroxides are colored.
  • B superoxides are paramagnetic.
  • C oxides are paramagnetic.
  • D peroxides are both colored and paramagnetic.

Step-by-Step Verified Solution

The peroxide and oxides of alkali metals are colourless when pure.

Superoxides are paramagnetic while peroxides are diamagnetic. Electronic configuration of O22−\mathrm{O}_{2}^{2-} (peroxide)

(σ1s2)(σ∗1s2)(σ2s2)(σ∗2s2)(σ2pz2)(π2px2π2py2)\left(\sigma 1 s^{2}\right)\left(\sigma^{*} 1 s^{2}\right)\left(\sigma 2 s^{2}\right)\left(\sigma^{*} 2 s^{2}\right)\left(\sigma 2 p_{z}^{2}\right)\left(\pi 2 p_{x}^{2} \pi 2 p_{y}^{2}\right) (π∗2px2π∗2py2)\left(\pi^{*} 2 p_{x}^{2} \pi^{*} 2 p_{y}^{2}\right)

Electronic configuration of O2−\mathrm{O}_{2}^{-}

(σ1s2)(σ∗1s2)(σ2s2)(σ∗2s2)(σ2pz2)(π2px2π2py2)\left(\sigma 1 s^{2}\right)\left(\sigma^{*} 1 s^{2}\right)\left(\sigma 2 s^{2}\right)\left(\sigma^{*} 2 s^{2}\right)\left(\sigma 2 p_{z}^{2}\right)\left(\pi 2 p_{x}^{2} \quad \pi 2 p_{y}^{2}\right) (π∗2px2π∗2py1)\left(\pi^{*} 2 p_{x}^{2} \pi^{*} 2 p_{y}^{1}\right)

superoxide is paramagnetic due 1 unpaired electron.

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