Final answer:
The chlorine-carbon-chlorine bond angle in C2Cl4 is about 120°, due to the trigonal planar geometry on the terminal carbon atoms that are sp² hybridized.
Step-by-step explanation:
The chlorines in the molecule C2Cl4 (tetrachloroethene) do not directly bond to each other, but are rather attached to the carbon atoms. The molecule features a linear arrangement for the central carbon atoms due to sp hybridization, with a bond angle of 180° between the carbons (C=C=C). Each carbon atom in C2Cl4 is bonded to two chlorine atoms. The geometry around each of these carbon atoms is trigonal planar, which results from sp² hybridization, and has characteristic bond angles of approximately 120°. Therefore, the chlorine-carbon-chlorine bond angle in C2Cl4 is about 120° around any of the terminal carbon atoms.