The chlorination of an alkane involves:

Options

A. Cl free radicals
B. `Cl^+` species
C. `Cl^-` species
D. `CH_4` free radicals

Answer

To solve the question regarding the chlorination of an alkane, we will analyze the process step by step.

### Step 1: Understanding the Reaction
The chlorination of an alkane involves the reaction of an alkane (like methane, CH₄) with chlorine gas (Cl₂) to form an alkyl chloride (like CH₃Cl). This reaction is a substitution reaction where hydrogen atoms in the alkane are replaced by chlorine atoms.

**Hint:** Identify the reactants and products involved in the chlorination process.

### Step 2: Mechanism of the Reaction
The chlorination of an alkane proceeds through a free radical mechanism, which consists of three main steps: initiation, propagation, and termination.

**Hint:** Familiarize yourself with the three steps of the free radical mechanism.

### Step 3: Initiation Step
In the initiation step, the chlorine molecule (Cl₂) undergoes homolytic cleavage in the presence of light or heat. This means that the bond between the two chlorine atoms breaks evenly, resulting in the formation of two chlorine free radicals (Cl•).

**Hint:** Remember that homolytic cleavage results in the formation of free radicals.

### Step 4: Propagation Steps
In the propagation steps, the chlorine free radicals react with the alkane. The first reaction involves a chlorine free radical attacking the methane molecule (CH₄), leading to the formation of hydrochloric acid (HCl) and a methyl free radical (CH₃•).

1. Cl• + CH₄ → HCl + CH₃•

Then, the methyl free radical can react with another chlorine molecule to form methyl chloride (CH₃Cl) and regenerate another chlorine free radical.

2. CH₃• + Cl₂ → CH₃Cl + Cl•

**Hint:** Understand how free radicals are generated and consumed in the propagation steps.

### Step 5: Termination Step
In the termination step, two free radicals can combine to form a stable product. For example, two chlorine free radicals can combine to form Cl₂, or a methyl free radical can combine with a chlorine free radical to form methyl chloride.

**Hint:** Recall that termination steps reduce the number of free radicals in the reaction mixture.

### Conclusion
The chlorination of an alkane primarily involves chlorine free radicals (Cl•) as key intermediates in the reaction mechanism. Therefore, the correct answer to the question is that the chlorination of an alkane involves Cl free radicals.

**Final Answer:** The chlorination of an alkane involves Cl free radicals.