When $\psi_{\mathrm{A}}$ and $\Psi_{\mathrm{B}}$ are the wave functions of atomic orbitals, then $\sigma^*$ is represented by :

Out of the following which has smallest bond length

The total number of molecular orbitals formed from $2 \mathrm{~s}$ and $2 \mathrm{p}$ atomic orbitals of a diatomic molecule

In which of the following transformations, the bond order has increased and the  magnetic behaviour has changed?

Give electron configuration, bond order and magnetic property, energy diagram in $\mathrm{MO}$ for Helium $\left( {{\rm{H}}{{\rm{e}}_2}} \right)$ molecule.