Brief about the chapter sound?

Sound is an energy

Sound propagate(means aage badna) in wave form 

Wave form means aapne kabhi patther fenka hai taalaab main

After throwing stones you can see circular wave 

When you want to walk you need a medium which is called land 

In such a way to propagate sound they need air , water and land which is called medium

Islia moon per air no hone ki wajah se we are not be able to heard sound on moon