Figure 8 represents a longitudinal wave. Which point is at the centre of a rarefaction?

In a longitudinal wave, like a sound wave, the vibrations are parallel to the direction of energy transfer. This creates areas where the particles of the medium are bunched together, called compressions, and areas where they are spread apart, called rarefactions. - Point E is in a region where the dots are dense, which is a compression. - Point F is in a region where the dots are spread out, which is a rarefaction. - Point G is also in a region where the dots are spread out, a rarefaction. The question asks for one point, and F is a valid choice.