Which geometry corresponds to sp hybridization?

• A. Trigonal planar
• B. Linear
• C. Tetrahedral
• D. Octahedral

Answer: (B)

The main idea is that sp hybridization forms two equivalent orbitals by mixing one s and one p orbital, and these two orbitals are oriented 180° apart. This creates two regions of electron density around the central atom, arranged in a straight line, which gives linear geometry.

If there are exactly two electron domains (for example, two bonds or a bond and a lone pair) around the central atom, the lowest-energy arrangement is linear, and the central atom uses sp hybrids to accommodate those two regions. The remaining two p orbitals stay unhybridized and can participate in π bonding, supporting multiple bonds when applicable.

Trigonal planar comes from sp2 hybridization (three regions, about 120°). Tetrahedral comes from sp3 (four regions, about 109.5°). Octahedral comes from sp3d2 (six regions).