What is the excited state of carbon?

The ground state electron configuration of carbon is ${\text{1""s"^"2""2s"^"2"2"""p}}^{2}$. An excited state electron configuration of carbon is $\text{1""s"^"2""2s"^1"2p"^3}$. This is the state of carbon when it undergoes chemical bonding to form four covalent bonds, as in methane, $\text{CH"_"4}$. However, the experimental evidence shows that all four bonds have the same energy, which can only be explained by the concept that the 2s and 2p orbitals hybridize to form four ${\text{sp}}^{3}$ orbitals, each with one unpaired electron.