When methane reacts with chlorine under UV light, what is the major product?

• A. Chloromethane + Hydrogen Chloride
• B. Dichloromethane
• C. Methane
• D. Chlorine gas

Answer: (A)

This is about free radical halogenation of methane under UV light. Chlorine molecules split to form chlorine radicals, which quickly attack one hydrogen from methane to give hydrogen chloride and a methyl radical. That methyl radical then grabs a chlorine atom to form chloromethane, while regenerating a chlorine radical to continue the chain. The first substitution is the most likely outcome under these conditions, so chloromethane (with HCl) is the major product. If more chlorine is present, further substitutions can occur to make dichloromethane or more chlorinated products, but the initial, dominant product is chloromethane. Chlorine gas is a reagent, not a product, and methane would only be left if no reaction happened.