Assertion: Liquids and gases are largely incompressible and densities are therefore, nearly constant at all pressure.
Reason: Liquids exhibit a large variation in densities with pressure by gases do not.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true and reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Analyze the Assertion
The assertion states that "Liquids and gases are largely incompressible and densities are therefore nearly constant at all pressure."

- **Understanding Incompressibility**: Liquids are generally considered incompressible because their molecules are closely packed together, making it difficult to compress them further. However, gases are compressible because their molecules are far apart, allowing them to be compressed significantly under pressure.

- **Density Variation**: While the density of liquids does change slightly with pressure, it is relatively constant compared to gases. For gases, density can change significantly with pressure changes.

### Conclusion on Assertion
The assertion is incorrect because it implies that both liquids and gases are largely incompressible, which is not true. Gases are compressible.

### Step 2: Analyze the Reason
The reason states that "Liquids exhibit a large variation in densities with pressure, but gases do not."

- **Density Variation in Liquids**: The density of liquids does change with pressure, but this change is minimal. For practical purposes, liquids can be treated as having constant density under normal conditions.

- **Density Variation in Gases**: For gases, density changes significantly with pressure, especially under varying temperature conditions. According to the ideal gas law, density is directly proportional to pressure when temperature is held constant.

### Conclusion on Reason
The reason is also incorrect because it states that gases do not exhibit a variation in density with pressure, which is false. Gases do show significant variations in density with pressure.

### Final Conclusion
Both the assertion and the reason are incorrect. Therefore, the correct answer is that neither the assertion nor the reason is true.

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