Question

Write the differences between compression and rarefaction?

Answer 1

When particles come together , they form a compression.When they move away, they form Rare fraction.
Compressions are regions of high density and high pressure.Rarefactions are regions of low density and low pressure.

Answer 2

compression is the region of high pressure or high density
while,
rarefaction is the region of low pressure and low density 

i hope it helps........