Which reagent will you use for the following reaction.
`CH_3CH_2CH_2CH_3 rarrCH_3CH_2CH_2CH_2Cl+CH_3CH_2CHClCH_3`

Options

A. `Cl_2//UV` light
B. `NaCl+H_2SO_4`
C. `Cl_2` gas in dark
D. `Cl_2` ga in the presence of iron in dark

Explanation

To solve the question regarding the reagent used for the reaction of butane to produce 1-chlorobutane and 2-chlorobutane, we can follow these steps:

### Step 1: Identify the Reactants and Products
The reactant given is butane, which has the formula CH₃CH₂CH₂CH₃. The products are 1-chlorobutane (CH₃CH₂CH₂CH₂Cl) and 2-chlorobutane (CH₃CH₂CHClCH₃).

### Step 2: Understand the Type of Reaction
This reaction is a halogenation reaction, specifically the chlorination of an alkane. In this case, butane is being chlorinated to form chlorinated butanes.

### Step 3: Determine the Conditions Required for the Reaction
Chlorination of alkanes typically requires the presence of chlorine (Cl₂) and a source of energy to initiate the reaction. This energy can be provided by UV light, which facilitates the breaking of the Cl-Cl bond to form chlorine radicals.

### Step 4: Identify the Mechanism of the Reaction
The chlorination occurs through a radical mechanism, which involves:
- **Chain Initiation**: The Cl₂ molecule is dissociated into two chlorine radicals in the presence of UV light.
- **Chain Propagation**: The chlorine radicals react with butane, abstracting hydrogen atoms and forming new radicals, which can further react with chlorine radicals to produce chlorinated products.
- **Chain Termination**: The reaction can terminate when two radicals combine.

### Step 5: Select the Correct Reagent
Given the options provided:
1. Cl₂ + UV light
2. NaCl + H₂SO₄
3. Cl₂ + GaAs in dark
4. Cl₂ + GaAs + Iron in dark

The correct reagent for this reaction is **Cl₂ in the presence of UV light**. This is because direct halogenation of alkanes occurs effectively under these conditions.

### Final Answer
The reagent used for the reaction is **Cl₂ in the presence of UV light**.

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