Answer:
Compression is that part of longitudinal wave in which the medium of particles are closer and there is momentary decrease in volume of medium.
Rarefaction is that part of longitudinal wave in which the medium of particles apart and there is momentary increase in volume of medium.
Compression is that part in which particles vibrating in a medium come closer to each other and rarefaction is that part in which particles vibrating in a medium move apart from each other .
