Name the sodium compound which is used for softening hard water.

Explanation

To solve the question, "Name the sodium compound which is used for softening hard water," we can follow these steps:

### Step-by-Step Solution:

1. **Understand Hard Water**:
- Hard water is water that contains high levels of dissolved minerals, primarily calcium (Ca²⁺) and magnesium (Mg²⁺) ions. These minerals can cause problems in household tasks, such as forming scale in pipes and not allowing soap to lather effectively.

2. **Identify the Problem**:
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