Statement-1 : Vacuum is densest for sound and rarest for light
Statement-2 : A medium is said to be denser, when velocity of waves through this medium is smaller

Options

A. Statement-1 is true, Statement-2 is true , Statement-2 is correct explanation for Statement-3
B. Statement-1 is true,Statement-2 is true , Statement-2 is NOT a correct explanation for Statement-3
C. Statement-1 is true, Statement-2 is false
D. Statement-1 is false, Statement-2 is true

Answer

To analyze the given statements, we will break down the concepts of wave propagation in different media, specifically focusing on sound and light.

### Step-by-Step Solution:

1. **Understanding Statement 1**:
- The first statement claims that "Vacuum is densest for sound and rarest for light."
- Sound requires a medium to propagate; it cannot travel through a vacuum. Therefore, the speed of sound in a vacuum is effectively zero.
- Since sound cannot exist in a vacuum, we can infer that the concept of "density" for sound in a vacuum is not applicable in the traditional sense. However, in terms of refractive index, we can say that the effective refractive index for sound in a vacuum is infinite, which suggests it is "densest" in terms of the inability to propagate.

2. **Understanding Statement 2**:
- The second statement claims that "A medium is said to be denser when the velocity of waves through this medium is smaller."
- This is true for both sound and light. The refractive index (n) of a medium is given by the formula:
\[ n = \frac{c}{v} \]
where \( c \) is the speed of light in vacuum and \( v \) is the speed of light in the medium. A higher refractive index indicates a denser medium, which corresponds to a lower speed of light in that medium.
- For sound, a similar relationship holds. A medium with a lower speed of sound compared to another medium is considered denser.

3. **Conclusion**:
- Both statements are true based on the definitions of density in terms of wave propagation.
- Statement 1 is true because vacuum cannot support sound, making it "densest" in a conceptual sense, while it is "rarest" for light since light travels fastest in vacuum.
- Statement 2 is true as it accurately describes the relationship between wave velocity and medium density.

### Final Answer:
Both statements are true, and Statement 2 provides the correct explanation for Statement 1.