MCQ
In which of the following pairs of molecules/ions, both the species are not likely to exist?
- A$H_{2}^+, He_2^{2-}$
- B$H_{2}^-, He_2^{2-}$
- ✓$H_{2}^{+2}, He_2$
- D$H_{2}^-, He_2^{2+}$
$\mathrm{H}_{2}^{2+}(1+1-2=0)=\sigma 1 \mathrm{s}^{0}$
Bond order $=0$
$\mathrm{He}_{2}(2+2=4)=\sigma 1 \mathrm{s}^{2},{ }^{\star} \mathrm{fs}^{2}$
Bond order $=\frac{N_{0}-N_{a}}{2}=\frac{2-2}{2}=0$
$\mathrm{So}, \mathrm{both} \mathrm{H}_{2}^{2+}$ and $\mathrm{He}_{2}$ do not exist.
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$C{H_3} - C \equiv C - C{H_3}\xrightarrow{{{H_2}/Pd - BaS{O_4}}}$ $A\xrightarrow{{B{r_2}/CC{l_4}}}C$
$C{H_3} - C \equiv C - C{H_3}\xrightarrow{{Na/Liq.\,N{H_3}}}$ $B\xrightarrow{{B{r_2}/{H_2}O}}D$
$A : 3\,, 2\,, -2\,, +\, \frac{1}{2}$
$B : 3\,, 0\,, 0\,, + \,\frac{1}{2}$
What is true for $A$ and $B$