Q47 / 180 · NEET 2020 (Phase 1) · Chemistry

Identify a molecule which does not exist.

A
${Li}_{2}$
B
$C_{2}$
C
$O_{2}$
Correct answer
D
${He}_{2}$

Solution

${He}_{2} =$ Total electron $= 4$

$= σ_{1 s^{2}}^{} σ_{1 s^{2}}^{*} \Rightarrow B . O . = \frac{1}{2} [Nb - Na] = \frac{1}{2} [2 - 2] = 0$

Bond order $= 0$ , so ${He}_{2}$ does not exist.

Hence, the correct answer is option: 'D'.

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