Assertion In He-Nelaser, population inversion takes place between energy levels of neon atoms.
Reason Helium atoms have a metastable energy level.

Options

A. Both assertion and reason are true and reason is the correct explanation of assertion
B. Both assertion and reason are true but reason is not the correct explanation of assertion
C. Assertion is true but reason is flase
D. Both assertion and reason are false

Explanation

To solve the question regarding the assertion and reason related to the He-Ne laser, we will analyze both statements step by step.

### Step 1: Understanding the Assertion
The assertion states that "In He-Ne laser, population inversion takes place between energy levels of neon atoms."

**Explanation**:
In a He-Ne laser, the process of population inversion occurs when a higher number of atoms are in an excited state compared to a lower energy state. In this case, it is specifically referring to the neon atoms. The population inversion is crucial for laser action, as it allows for stimulated emission to dominate over absorption.

### Step 2: Understanding the Reason
The reason states that "Helium atoms have a metastable energy level."

**Explanation**:
Helium atoms, when excited by an electric discharge, can reach a metastable state. This state is not the highest energy state but is long-lived compared to other excited states. The metastable state allows helium atoms to transfer energy to neon atoms effectively, facilitating the population inversion in neon.

### Step 3: Analyzing the Relationship Between Assertion and Reason
Now, we need to determine if the reason supports the assertion.

- The assertion is correct because population inversion does take place in the neon atoms.
- The reason is also correct because helium atoms indeed have a metastable energy level that plays a crucial role in achieving the population inversion in neon atoms.

### Conclusion
Both the assertion and the reason are correct, and the reason provides a valid explanation for the assertion. Therefore, the correct answer is:

**Correct Option: A (Both Assertion and Reason are correct, and Reason is the correct explanation for Assertion)**

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