If there is bonding between two atoms where one atom is having one vacant orbital and another is having one lone pair of electrons, then if this electron pair is donated to that respective vacant orbital then the bonding is called p(pie) - p(pie) or p(pie) - d(pie) depending on the orbital to which the electron pair is donated and from which the electron pair is donated. In SO2 there are 1p-pi and 1p-pi-dpi bond.
There are 3(Pπ-Pπ ) & 1(Pπ-dπ) Bonds In SO2 Molecule. Because 3 orbitals of P-subshell of S Overlap With 3 Orbitals of P-subshell of O2 & 1 Orbital of d-subshell of S Overlap With 1 orbital of P-subshell of O2........ Hence Proved......🙌🏻✨✔️