(a) Hybrid orbitals do not form $ \sigma$ bonds
(b) Laternal overlap of p-orbitals or p- and d-orbitals produces $\pi$ bonds
(c) The strength of bonds follows the order:
$\sigma_{p-p} < \sigma_ {s -s} < \pi _{p-p}$
(d) s-orbitals do not form $\sigma$ bonds