1. Tardigrade
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  3. Chemistry
  4. Identify a molecule which does not exist.

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Q. Identify a molecule which does not exist.

NEETNEET 2020Chemical Bonding and Molecular Structure

Solution:

Species in which bond order is zero do not exist.
(1) $O_2 = (KK)(\sigma 2s^2)(\sigma^* 2s^2)(\sigma 2p_z^2)$
$(\pi 2p_x^2 = \pi 2p_y^2)( \pi^* 2p_x^1 = \pi^* 2p_y^1)$
Bond Order $ = \frac{10 - 6}{2} = 2$
(2) $He_2 = (\sigma 1s^2)(\sigma^* 1s^2)$
Bond Order $= 0$
(3) $Li_2 = (\sigma1s^2)(\sigma^* 1s^2)(\sigma^* 2s^2)$
Bond Order $= 1$
(4) $C_2 = (\sigma 1s^2)(\sigma^* 1s^2)(\sigma 2s^2)(\sigma^* 2s^2)$
$(\pi 2p_x^2 = \pi 2p_y^2)$
Bond Order $= 2$
As, bond order of $He_2$ is zero it does not exist.