In which hybridization does carbon have four unpaired electrons?

In sp3 hybridization, carbon exhibits four unpaired electrons, allowing it to form four equivalent sigma bonds with other atoms. This hybridization occurs when one s orbital and three p orbitals combine to create four sp3 hybrid orbitals, each containing one unpaired electron. This configuration is crucial for carbon's ability to bond in molecules such as methane (CH4), where it forms four strong bonds with hydrogen atoms.

In contrast, sp hybridization involves the mixing of one s orbital with one p orbital, resulting in two hybrid orbitals, each containing one unpaired electron. This leads to the formation of linear structures, not allowing for four unpaired electrons. Similarly, sp2 hybridization combines one s orbital with two p orbitals, resulting in three sp2 hybrid orbitals, also leading to a configuration that does not support four unpaired electrons, as one p orbital is left unhybridized. Therefore, sp3 hybridization is the only type where carbon can have four unpaired electrons, facilitating the formation of four bonds.