When an electron moves from one energy level to another, if the transition is to a energy level, energy is absorbed, and a photon is by the atom. Question 16 options:
higher; absorbed
lower; emitted
lower; absorbed
higher; emitted

lower,emitted

Explanation:

when electron changes level,  it decreases energy and emits photon.

photon is emitted when it goes from higher to lower energy level

the population of unionid mussels in the hudson river decreased after zebra mussels were introduced. zebra mussels, a nonnative species, competed with the unionid mussels for food. the zebra mussels were able to outcompete the unionid mussels, allowing the zebra mussel population to increase dramatically over six years. the unionid mussel population decreased due to a lack of food.

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