What happens to the molecules of a medium during
(a) compression and
(b) rarefaction ?

Explanation

To answer the question about what happens to the molecules of a medium during compression and rarefaction, we can break it down into two parts:

### Step-by-Step Solution:

**(a) Compression:**
1. **Definition of Compression**: Compression occurs when the molecules of a medium are pressed together.
2. **Molecular Behavior**: During compression, the molecules of the medium are forced closer to each other.
3. **Energy Transfer**: As the molecules are compressed, they gain kinetic energy due to the increased pressure.
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