Question

question 2: alex is developing models to explain how matter is classified. what is required in her model of a compound? the substance is composed of at least two different elements. the atoms in the substance are held together in chemical bonds. the particles of the substance do not move freely past each other. the substance is composed of at least one element that is a metal.

Explanation:

A compound is defined as a substance made up of at least two different elements chemically bonded together. Option A only mentions elements composition, option C is about particle movement (more related to states of matter), and option D is too restrictive as compounds don't have to contain a metal. Option B correctly states that atoms in a compound are held together by chemical bonds, which is a key characteristic of compounds.

Answer:

B. The atoms in the substance are held together in chemical bonds.