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In which of the following pairs of molecules/ions both the species are not likely to exist?

$H_{2}^{+},He_{2}^{2-}$

$H_{2}^{-},He_{2}^{2-}$

$H_{2}^{2+},He_{2}^{}$

$H_{2}^{-},He_{2}^{2+}$

Option C

Species having zero or negative bond order do not exist

$H_{2}^{2+}$ (1+1-2=0)= $\sigma 1s^{0}$

Bond order =0

$He_{2}^{}$ (2+2=4)= $\sigma 1s^{2},\sigma^{*}1s^{2}$

Bond order = $\frac{N_{b}-N_{a}}{2}$

= $\frac{2-2}{2}=0$

so, both $H_{2}^{2+}$ and $He_{2}^{}$ do not exist.

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