Final answer:
The hybridization scheme that can form at least one π bond is SP² hybridization which has an unhybridized p orbital that can overlap with another p orbital to form a π bond. The correct answer is option: b. SP²
Step-by-step explanation:
The hybridization scheme that allows the formation of at least one π (pi) bond is SP². This hybridization involves the mixing of one s orbital and two p orbitals to form three sp² hybrid orbitals that are arranged in a trigonal planar geometry.
The fourth p orbital remains unhybridized and is perpendicular to the plane of the sp² orbitals, allowing it to overlap sideways (also known as lateral or parallel overlap) with an adjacent p orbital to form a π bond, such as in the molecule ethene (C₂H₄).