What is an acid ? Name any two acids. How can you test the presence of an acid in a substance?

Explanation

### Step-by-Step Solution:

1. **Definition of an Acid:**
An acid is a substance that has a sour taste and can donate hydrogen ions (H⁺) when dissolved in water. In aqueous solutions, acids produce H⁺ ions, which is the characteristic that defines them.

2. **Examples of Acids:**
Two common examples of acids are:
- Hydrochloric Acid (HCl)
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