¿Qué es una reacción exotérmica?

When will le chatelier's principle come into effect? at the beginning of a reaction, when there are only reactants when a reaction has reached chemical equilibrium when a catalyst is added to a reaction mixture when a reaction is occurring but not yet at equilibrium

Several kinds of bears are found on earth. most bears are brown or black, but one type of bear, the polar bear, is white. what process led to this difference in fur color? explain your answer.

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.