Which of the following are incorrect?

Options

A. At altitude, the pressure of air is low
B. At altitude, the density of air is low
C. At altitude, cooking takes place slower
D. At altitude, water will boil at temperature greater than `100^(@)C`.

Explanation

To determine which statements are incorrect regarding the behavior of gases and liquids at altitude, we will analyze each statement step by step.

### Step-by-Step Solution:

1. **Understanding Atmospheric Pressure at Altitude:**
- At higher altitudes, the atmospheric pressure decreases. This is due to the fact that there is less air above you, which results in lower pressure.
- **Conclusion:** The statement "At altitude, the pressure of air is low" is **true**.

2. **Effect of Pressure on Density:**
- Density is directly proportional to atmospheric pressure. If the atmospheric pressure decreases, the density of air also decreases.
- **Conclusion:** The statement regarding the decrease in density at altitude is **true**.

3. **Boiling Point of Water and Pressure Relationship:**
- The boiling point of water decreases with a decrease in atmospheric pressure. This means that at higher altitudes, water will boil at a temperature lower than 100°C.
- **Conclusion:** The statement "At altitude, water will boil at a temperature greater than 100°C" is **incorrect** because the boiling point actually decreases.

4. **Cooking at Altitude:**
- Cooking takes longer at higher altitudes because the boiling point of water is lower. This means that food may not cook as effectively since the water does not reach as high a temperature as it would at sea level.
- **Conclusion:** The statement "At altitude, cooking takes place slower" is **true**.

### Final Answer:
The incorrect statement is: "At altitude, water will boil at a temperature greater than 100°C."