Acompound composed of two oppositely charged elements.

Skills of homo sapiens were found an excavation. the skulls were preserved because the bodies were frozen. so, these fossils are (blank) fossils.the image shows the evolution of skulls beginning 2 to 3 million years ago. based on the image, modern human skulls(blank) ape skulls.

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

According to le chatelier’s principle, a system in chemical equilibrium responds to stress by shifting the equilibrium in a direction that reduces the stress. normalizes the stress. increases the stress. changes the stress.