MCQ
Which of the following is paramagnetic ?
  • $O_2[AsF_6]$
  • B
    $Al_2O_3$
  • C
    $C_2$
  • D
    $Be_2$

Answer

Correct option: A.
$O_2[AsF_6]$
a
In $\mathrm{O}_{2}\left[\mathrm{AsF}_{6}\right], \mathrm{O}_{2}^{+}$ ion have one unpaired electron. $\mathrm{Al}_{2} \mathrm{O}_{3}$ is oxide in which $\mathrm{Al}^{3+}$ and $\mathrm{O}^{2-}$ ion do not have any unpaired electrons.

$\mathrm{C}_{2}=\sigma 1 \mathrm{s}^{2}, \sigma^{*} 1 \mathrm{s}^{2}, \sigma 2 \mathrm{s}^{2}, \sigma^{*} 2 \mathrm{s}^{2}, \pi 2 \mathrm{p}_{\mathrm{x}}^{2}, \pi 2 \mathrm{p}_{\mathrm{y}}^{2}$

Number unpaired electrons.

$\mathrm{Be}_{2}=\sigma 1 \mathrm{s}^{2}, \sigma^{*} 1 \mathrm{s}^{2}, \sigma 2 \mathrm{s}^{2}, \sigma^{*} 2 \mathrm{s}^{2}$

No unpaired electrons.

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