If the relative humidity of the air is 47 nd its temperature is 68 ∘f, how many molecules of water are present in a room measuring 11 × 12 × 11 ft ?.

Sounds propagates through some kind of medium. usually it's air, but it goes just as well through solid objects like walls, windows etc. a soundwave will compress the (air)molecules in front of it, and if this increased density wave hits your ears, you register it as sound. solid objects like walls are a lot denser than air, this means that they will damp a wave, but also carry it easier.

Maybe because they hurt or you bleed a lot