Answer:
The answer is Atom.
Explanation:
The atom is the smallest constituent unit of matter that has the properties of a chemical element and that it is not possible to divide by chemical processes. The atom is formed by a nucleus with protons and neutrons and several orbital electrons (subatomic particles); whose number varies according to the chemical element. Atoms combine to form molecules that then interact to form solids, liquids and gases.
The number post-reproductive age group will decline in number in a population pyramid.
<h3>What is a population?</h3>
A population is a group of organisms of the same same specie living in a defined area of a given habitat.
A population pyramid shows the number of organisms of age groups in a population.
The post-productive age group is characterized by individuals that are too old to have children.
Since they are too old to have children, the post-reproductive age group will decline in number.
Learn more about population at: brainly.com/question/25896797
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