When an ant stings a person, the solution of substance A is rubbed on the stung area of the skin to get relief from pain. The substance A is also used in kitchen for cooking purposes. Another susbtance B is sour in taste and contains an organic acid C. It is used in making pickles. When a solution of A is mixed with B, then a change D takes place to produce bubbles of gas E.
What are substances B ?

Answer

To solve the question, we need to identify substance B based on the information provided. Let's break down the information step by step.

### Step-by-Step Solution:

1. **Understanding Substance A**:
- Substance A is used to relieve pain from an ant sting.
- It is mentioned that it is a solution and is also used in cooking.
- Given that ant venom is acidic, a base is required to neutralize it.
- The common base used in cooking that can neutralize acids is **baking soda** (sodium bicarbonate, NaHCO3).

**Hint**: Think about common kitchen ingredients that can neutralize acidity.

2. **Identifying Substance B**:
- Substance B is described as sour in taste and contains an organic acid (substance C).
- It is also used in making pickles.
- A well-known sour substance that contains an organic acid and is commonly used in pickles is **vinegar**, which contains acetic acid (C) with the formula CH3COOH.

**Hint**: Consider common sour substances used in cooking and food preservation.

3. **Understanding the Reaction**:
- When a solution of A (baking soda) is mixed with B (vinegar), a chemical reaction occurs.
- This reaction produces bubbles of gas, which is carbon dioxide (CO2).
- The reaction can be summarized as:
\[ \text{NaHCO}_3 + \text{CH}_3\text{COOH} \rightarrow \text{CH}_3\text{COONa} + \text{H}_2\text{O} + \text{CO}_2 \uparrow \]
- Here, sodium acetate (CH3COONa), water (H2O), and carbon dioxide (CO2) are produced.

**Hint**: Think about what happens when an acid reacts with a base.

### Final Answer:
Substance B is **vinegar**.