Final answer:
The proper name for C₂Cl₄ is dicarbon tetrachloride, as the prefix 'di-' indicates two carbon atoms and 'tetra-' denotes four chlorine atoms.
Step-by-step explanation:
The proper name for the molecule with the formula C₂Cl₄ is dicarbon tetrachloride. When naming this molecular compound, since both carbon atoms are listed first due to their position in the periodic table relative to chlorine, the prefix 'di-' is used to indicate the two carbon atoms.
For the four chlorine atoms, the prefix 'tetra-' is employed, leading to 'tetrachloride.' The complete name combines these to state dicarbon tetrachloride, differentiating it from carbon tetrachloride, which implies only one carbon atom is present, as in the compound CCl₄.