Why should curd and sour substances not be kept in brass and copper vessels?

Explanation

**Step-by-Step Solution:**

1. **Identify the Nature of Curd and Sour Substances:**
- Curd and sour substances are acidic in nature. This means they have a pH value of less than 7 and contain hydrogen ions (H⁺).

2. **Understand the Composition of Brass and Copper:**
- Brass is an alloy made primarily of copper and zinc. Copper itself is a metal that can react with acids.

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