The salt `Na_(2) HPO_(4)` is formed when orthophosphoric acid is reacted with an alkali. Find the equivalent weight of orthophosphoric acid.

Explanation

To find the equivalent weight of orthophosphoric acid (H₃PO₄) when it reacts with an alkali to form the salt Na₂HPO₄, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Acid and Its Formula**:
- The orthophosphoric acid is represented by the formula H₃PO₄.

2. **Understand the Reaction**:
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