Bond energy is highest in the overlapping.

$sp-s$ has the highest bond energy of overlapping.

- s orbitals hold electrons more tightly to the nucleus than p orbitals.
- The greater the s character, the closer are the electrons to the nucleus.
- The greater the s character, the shorter and stronger is the bond.
- Shorter and stronger bonds signify more overlapping between orbitals.
- Due to all these reasons, bond length in ${\mathrm{sp}}^3$ hybridized atoms is greater than ${\mathrm{sp}}^2$and $\mathrm{sp}$ hybridized atoms, and bond strength in ${\mathrm{sp}}^2$ hybridized atoms is less than ${\mathrm{sp}}^2$ and $\mathrm{sp}$ hybridized atoms.