Question

multiple choice question
a pure chemical substance consisting of two or more atoms of the same element is most correctly called an
compound
molecule
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Explanation:

A compound consists of different elements chemically combined. A molecule is a group of two or more atoms held together by chemical bonds, and it can be of the same element (e.g., $O_2$) or different elements. Since the question refers to a pure substance of the same - element atoms, it is a molecule.

Answer:

B. molecule