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In the human digestive system, food enters the mouth and mechanical digestion of the food starts by the action of mastication (chewing), a form of mechanical digestion, and the wetting contact of saliva.
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Answer:
In chemistry and quantum mechanics, an orbital is a mathematical function that <u><em>describes the wave-like behavior of an electron, electron pair</em></u>, or (less commonly) nucleons. An orbital may also be called an atomic orbital or electron orbital.
Explanation:
BRAINLIEST?
Natural selection it has to be 20 characters so disreguard the rest
