Answer:
1. In a sound wave what is a region of high pressure known as?
These regions are known as compressions and rarefactions respectively. The compressions are regions of high air pressure while the rarefactions are regions of low air pressure.
2. Name a wave that does not need a material to travel
An electromagnetic wave can travel through anything - be it air, a solid material or vacuum. It does not need a medium to propagate or travel from one place to another.
3. Why does sound travel faster in solids as compared to liquids and faster in liquid as compared to gases?
This is because the molecules of solids are more tightly packed together than in liquids and those in liquids are more tightly packed than in gases. Vibrating effects are more easily passed on from one molecule to the next when they are in close proximity.
Step-by-step explanation:
Hope it helps! =D