_________ is formed when ultraviolet radiation decomposes chlorinated hydrocarbon.

• A. Carbon dioxide
• B. Argon
• C. Phosgene
• D. Ozone

Answer: (C)

Ultraviolet radiation packs enough energy to break the carbon–chlorine bonds in chlorinated hydrocarbons. When those bonds are cleaved, reactive fragments form and can combine with available oxygen to create carbonyl chloride, known as phosgene. This product specifically contains carbon, oxygen, and two chlorine atoms in a arrangement that matches the fragments produced by UV-induced breakdown of chlorinated solvents, making phosgene the likely outcome of this photolysis.

Carbon dioxide would require full oxidation of the carbon backbone, which isn’t the direct product of merely breaking C–Cl bonds. Argon is an inert gas and isn’t formed by chemical decomposition of organochlorines. Ozone forms from ultraviolet splitting of molecular oxygen, not from the breakdown of chlorinated hydrocarbons, so it isn’t the expected product here.