Which alkyl halide from the following pairs would you expect to react more rapidly by an `S_(N)2` mechanism? Explain your answer.
(i) `CH_(3)CH_(2)CH_(2)CH_(2)Br` or `CH_(3)CH_(2)underset(Br)underset(|)CHCH_(3)` (ii) `CH_(3)CH_(2)underset(Br)underset(|)CHCH_(3)` or `H_(2)C-underset(CH_(3))underset(|)overset(CH_(3))overset(|)C-Br`

Explanation

To determine which alkyl halide from the given pairs would react more rapidly by an `S_N2` mechanism, we need to analyze the structure of each alkyl halide and consider the steric hindrance around the carbon atom that is bonded to the halogen. The `S_N2` mechanism is favored by less sterically hindered (primary) alkyl halides, as the nucleophile can approach and attack the carbon more easily.

### Step-by-Step Solution:

**(i)** Compare `CH₃CH₂CH₂CH₂Br` (1-bromobutane) and `CH₃CH₂Br` (2-bromobutane).

1. **Identify the type of carbon attached to the halogen:**
- In `CH₃CH₂CH₂CH₂Br`, the bromine is attached to a primary carbon (the terminal carbon).
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