$\mathrm{H}_{2}^{2+}(1+1-2=0)=\sigma 1 \mathrm{s}^{0}$

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.