Initiation in free-radical substitution Steps:

• Recall that free-radical substitution of methane with chlorine starts with initiation under UV light.
• Identify initiation as breaking the Cl-Cl bond to form chlorine radicals.
• Recognize homolytic fission splits bonds evenly, producing two radicals.
• Match this to the option describing even splitting yielding Cl• species.

Why A is correct:

• Initiation involves homolytic fission of Cl₂ to form two Cl• radicals, as defined by free-radical mechanism where UV energy causes equal bond cleavage (Cl₂ → 2Cl•).

Why the others are wrong:

• B: Heterolytic fission produces ions like Cl⁺ and Cl⁻, not radicals, so it describes ionic mechanisms, not free-radical.
• C: Homolytic fission of H• occurs in propagation (from CH₄), not initiation.
• D: Heterolytic fission cannot produce CH₃• radical; it yields ions like CH₃⁺.

Final answer: A