Which among the following is based on the principle that boiling point decreases with decrease in atmosphere pressure?

Options

A. Cooking food at sea-level takes longer period of time
B. Cooking food at higher altitudes takes longer period of time
C. Working principle of air coolers
D. Working of pressure cooker.

Explanation

To solve the question "Which among the following is based on the principle that boiling point decreases with decrease in atmospheric pressure?", we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understand the Concept**:
- The boiling point of a liquid is the temperature at which its vapor pressure equals the atmospheric pressure. When the atmospheric pressure decreases, the boiling point of the liquid also decreases.

2. **Identify Relevant Scenarios**:
- Consider scenarios where atmospheric pressure is lower, such as at high altitudes. At higher altitudes, the atmospheric pressure is lower than at sea level, which means that the boiling point of water is lower.

3. **Examples of Applications**:
- **Cooking at High Altitudes**: When cooking at high altitudes, food takes longer to cook because the boiling point of water is lower, meaning water boils at a lower temperature.
- **Pressure Cookers**: In contrast, pressure cookers work by increasing the pressure inside the vessel, which raises the boiling point of water, allowing food to cook faster.

4. **Conclusion**:
- The principle that boiling point decreases with a decrease in atmospheric pressure is primarily observed in cooking at high altitudes. Therefore, the correct answer to the question is related to cooking methods that take place at high altitudes.

### Final Answer:
The principle that boiling point decreases with a decrease in atmospheric pressure is observed in cooking food at high altitudes.

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