Statement-1 surface wave and sky wave can not be observed on moon.
Statement-2: Atmosphere of variable refractive index is require for propagation of surface & sky wave.

Options

A. Statement-1 is true, statement-2 is true, statement-2 is 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.

Answer

To solve the question, we need to analyze both statements and understand the underlying concepts related to surface waves, sky waves, and the conditions required for their propagation.

### Step-by-Step Solution:

1. **Understanding Surface Waves and Sky Waves**:
- Surface waves are electromagnetic waves that travel along the surface of a medium, such as the Earth. They are typically used in radio communications.
- Sky waves are radio waves that are transmitted into the ionosphere and can be reflected back to Earth, allowing for long-distance communication.

2. **Analyzing Statement 1**:
- Statement 1 claims that surface waves and sky waves cannot be observed on the Moon. This is true because the Moon lacks a significant atmosphere.

3. **Understanding the Role of Atmosphere**:
- For both surface waves and sky waves to propagate effectively, a medium with a variable refractive index is necessary. The Earth's atmosphere provides this variable refractive index, which allows these waves to bend and reflect.

4. **Analyzing Statement 2**:
- Statement 2 states that an atmosphere with a variable refractive index is required for the propagation of surface and sky waves. This is also true, as the atmosphere plays a crucial role in the bending and reflection of these waves.

5. **Conclusion**:
- Since both statements are true and Statement 2 correctly explains why Statement 1 is true, we can conclude that both statements are valid. Therefore, the answer is that Statement 1 is true, Statement 2 is true, and Statement 2 correctly explains Statement 1.

### Final Answer:
- Statement 1: True
- Statement 2: True
- Reasoning: Statement 2 correctly explains why surface waves and sky waves cannot be observed on the Moon due to the absence of an atmosphere.