A: At very high pressures, compressibility factor is greater than 1.
R: At very high pressure, 'b' can be neglected in van der Waals gas equation

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To solve the question, we will analyze both the assertion (A) and the reason (R) provided.

### Step 1: Understanding the Assertion (A)
The assertion states that "At very high pressures, compressibility factor is greater than 1."

- The compressibility factor (Z) is defined as:
\[ Z = \frac{PV}{RT} \]
where P is pressure, V is volume, R is the ideal gas constant, and T is temperature.
- At high pressures, real gases deviate from ideal behavior. The compressibility factor (Z) becomes greater than 1, indicating that the gas is less compressible than an ideal gas.

### Step 2: Understanding the Reason (R)
The reason states that "At very high pressure, 'b' can be neglected in van der Waals gas equation."

- The van der Waals equation is given by:
\[ \left(P + \frac{a n^2}{V^2}\right)(V - nb) = nRT \]
- Here, 'a' accounts for the attraction between particles, and 'b' accounts for the volume occupied by the gas particles.
- At very high pressures, the volume (V) becomes very small, and the term 'b' (which represents the volume occupied by gas molecules) cannot be neglected. In fact, it becomes significant.

### Step 3: Analyzing the Truth of A and R
- From the analysis:
- The assertion (A) is **true** because at very high pressures, Z is indeed greater than 1.
- The reason (R) is **false** because at very high pressures, 'b' cannot be neglected.

### Conclusion
- Therefore, the assertion is true, but the reason is false.

### Final Answer
- Assertion (A) is true, and Reason (R) is false.