Assertion: In a container containing gas `'A'` at temperature `400 K`, some more gas `A` at temperature `400 K` is introduced. The pressure of the system increases.
Reason: Increase in gaseous particle increses the number of collisions among the molecules.

Options

A. Statement-1 is True, Statement-2 is True, Statement-2 is a correct explanation for Statement-1
B. Statement-1 is True, Statement-2 is True, Statement-2 is NOT a correct explanation for Statement-1
C. Statement-1 is True, Statement-2 is False.
D. Statement-1 is False, Statement-2 is True.

Explanation

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

### Step-by-Step Solution:

1. **Understanding the Assertion:**
- The assertion states that when gas 'A' at a temperature of 400 K is introduced into a container already containing gas 'A' at the same temperature, the pressure of the system increases.
- According to the ideal gas law, \( P = \frac{nRT}{V} \), where:
- \( P \) = pressure,
- \( n \) = number of moles,
- \( R \) = universal gas constant,
- \( T \) = temperature,
- \( V \) = volume.
- In this scenario, the volume (V) and temperature (T) remain constant while the number of moles (n) increases due to the addition of more gas 'A'.

2. **Analyzing the Effect on Pressure:**
- Since \( R \) and \( T \) are constants, an increase in the number of moles \( n \) will lead to an increase in pressure \( P \).
- Therefore, the assertion is **true**: the pressure of the system increases when more gas is added at the same temperature.

3. **Understanding the Reason:**
- The reason states that the increase in gaseous particles increases the number of collisions among the molecules.
- When more gas particles are present, the frequency of collisions between gas molecules indeed increases, which is a true statement.

4. **Evaluating the Relationship:**
- While both the assertion and the reason are true, we need to determine if the reason correctly explains the assertion.
- The pressure in a gas system is primarily due to the collisions of gas molecules with the walls of the container, not just between the gas molecules themselves.
- Therefore, while the increase in gaseous particles does lead to more collisions, it is the collisions with the walls of the container that directly contribute to the increase in pressure.

5. **Conclusion:**
- The assertion is true.
- The reason is true, but it does not correctly explain the assertion.
- Thus, we conclude that the correct answer is:
- Assertion: True
- Reason: True
- Reason is not the correct explanation of the assertion.

### Final Answer:
- Assertion: True
- Reason: True
- Reason is not the correct explanation of the assertion.

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