Which statement correctly describes sp3 hybridisation?

• A. Overlap of d orbitals to form sigma bonds
• B. Involves three p orbitals
• C. Mixing of one s and three p orbitals to form four equal sp3 orbitals
• D. Involves only p orbitals forming pi bonds

Answer: (C)

sp3 hybridisation is the way an atom explains the formation of four equivalent sigma bonds in a tetrahedral geometry. It happens when one s orbital mixes with three p orbitals to produce four new hybrid orbitals, all identical in energy and shape. These four sp3 orbitals point toward the corners of a tetrahedron, so they can form sigma bonds by head-on overlap with orbitals from other atoms. Each hybrid has 25% s character and 75% p character, which helps explain the bond angles of about 109.5° in many molecules like methane.

So the statement describing the mixing of one s and three p orbitals to form four equal sp3 orbitals is the correct description. The other statements don’t fit: d orbitals aren’t involved in sp3 bonding, only p orbitals do not form the four equivalent hybrids, and pi bonds arise from side-on overlap of p orbitals, not from sp3 hybrids forming sigma bonds.