Determine the hybridization of the central atom in CH4 and CCl4.

Carbon has 4 valence electrons.

In methane, the carbon atom forms 4 single bonds with 4 hydrogen atoms. There are no lone pairs on the carbon atom.
Total electron domains = 4 (4 bonding pairs + 0 lone pairs).

Four electron domains correspond to $\text{sp}^3$ hybridization.
The hybridization of carbon in methane is $\boxed{\text{sp}^3}$.

Carbon has 4 valence electrons.

In tetrachloromethane, the carbon atom forms 4 single bonds with 4 chlorine atoms. There are no lone pairs on the carbon atom.
Total electron domains = 4 (4 bonding pairs + 0 lone pairs).

Four electron domains correspond to $\text{sp}^3$ hybridization.
The hybridization of carbon in tetrachloromethane is $\boxed{\text{sp}^3}$.