Answer:

1. Like ocean waves, sound waves need a medium to travel through. Sound can travel through air because air is made of molecules. These molecules carry the sound waves by bumping into each other, like Dominoes knocking each other over. Sound can travel through anything made of molecules - even water!

2. A crest is a point on a surface wave where the displacement of the medium is at a maximum. A trough is the opposite of a crest, so the minimum or lowest point in a cycle.

3. Sublimation is changing from a solid to a gas, or a gas to a solid, without becoming a liquid in between. Materials are a store of internal energy , due to the motion of particles and the chemical bonds between them. When a substance is heated, its internal energy increases: the movement of its particles increases.  

Explanation:  PA BRAINLIEST PO

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