Question

Among the following molecules / ions, $C^{2-}_{2}, N^{2-}_{2}, O^{2-}_{2}, O_{2}$ which one is diamagnetic and has the shortest bond length?

• A. $C^{2-}_{2}$
• B. $N^{2-}_{2}$
• C. $O_{2}$
• D. $O^{2-}_{2}$

Answer 1

The Correct Option is A

$C_2^{2-}\:^{-\sigma }1s^{2\sigma* }\:1s^{2\sigma }\:2s^{2\sigma* }2s^2\left[^{\pi }2p_x^2\right]^{\sigma }2p^2$
$B.O=\frac{10-4}{2}=3\left(diamagnetic\right)$
$N^{2-}_2\:^{-\sigma }1s^{2\sigma *}\:1s^{2\sigma*}\:2s^{2\sigma }2s^2\left[^{\pi 2p^2_x=^{\pi }2p^2_y}\right]\left[^{\pi }2p^1_x=^{\pi* }2p^1_y\right]$
$B.O=\frac{10-6}{2}2\left(paramagnetic\right)$
$O^{2-}_2\:^{-\sigma }1s^{2\sigma }1s^{2\sigma }2s^{2\sigma }2s^{2\sigma }2p^2_z\left[^{\pi }2p^2_x=^{\pi }2p^2_y\right]\left[^{\pi }2p^2_x=^{\pi* }2p^2_y\right]$
$B.O=\frac{10-8}{2}=1\left(diamagnetic\right)$
$O_{2} ^{-\sigma}1s^{2\sigma*}1s^{2\sigma}2s^{2\sigma*}2s^{2\sigma}2p^{2}_{z}\left[^{\pi}2p^{2}_{x}=^{\pi}2p^{2}_{y}\right]\left[^{\pi}2p^{1}_{x}=^{\pi*}2p^{1}_{y}\right]$
$B.O=\frac{10-6}{2}2\left(paramagnetic\right)$