What is an antacid ? How does an antacid work ? Name any one antacid.

Explanation

### Step-by-Step Solution:

1. **Definition of Antacid**:
An antacid is a substance that neutralizes stomach acidity. It is commonly used to relieve symptoms of indigestion and heartburn.

2. **How Antacids Work**:
Antacids are typically basic in nature. When they are ingested, they react with the excess stomach acid (which is acidic) to neutralize it. This reaction produces salt and water. The formation of salt and water helps to alleviate the discomfort caused by excess acidity in the stomach.

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