Question

Why the sound travel faster in a solid than in air an why it can't travel in vaccum

Answer 1

Solids have greater elastic constant than liquid which in turn has greater elastic constant than gases. Moreover, molecules in solids are more closely spaced so they strike the nearby molecules in less time and therefore wave propagates faster in solids.

Sound cannot travel through a vacuum. A vacuum is an area without any air, like space. So sound cannot travel through space because there is no matter for the vibrations to work in.