Using your knowledge of the reflection, absorption, and transmission of mechanical waves, Why do you think the foam is used, and how do you think it functions?

Anthracite is so hard and pure it is also referred to as a renewable resource metamorphic rock hot bituminous coal dirty fuel

The atom fluorine generally will become stable through the formation of an ionic chemical compound by accepting electron(s) from another atom. this process will fill its outer energy level of electrons.

The ammonia molecule in the diagram has the observed bond orientation because