Answer: A region of a longitudinal wave where the medium is spaced far apart is known as Rarefaction.
Step-by-step explanation:
A longitudinal wave is the one which requires medium to travel. The medium particles vibrate parallel to the direction of wave propagation. A longitudinal wave travels in the form of compression and rarefaction. A high density region of longitudinal wave is known as compression and a low density region is known as rarefaction. The medium is spaced apart in this region.