Explain: `CH_(2) = CH^(-)` is more basic than `HC -= C^(-)`.

Explanation

To explain why the anion \( \text{CH}_2 = \text{CH}^- \) is more basic than \( \text{HC} \equiv \text{C}^- \), we can analyze the acidity of the corresponding acids and the stability of the anions formed.

### Step-by-Step Solution:

1. **Identify the Structures**:
- The anion \( \text{CH}_2 = \text{CH}^- \) corresponds to the alkene ethylene (ethene) where one hydrogen is removed, resulting in a double bond between the two carbon atoms.
- The anion \( \text{HC} \equiv \text{C}^- \) corresponds to the alkyne acetylene where one hydrogen is removed, resulting in a triple bond between the two carbon atoms.

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