Which statement correctly describes why a compound is a pure substance?

A compound is a pure substance because its molecule cannot be broken down into simpler particles by physical means.

Explanation:

A pure substance is one whose composition does not vary, even if the physical conditions in which it is found change. For example, water has a formula that is H2O and is always the same, which indicates that it is made up of molecules in which there are 2 hydrogen atoms and 1 oxygen atom. If that formula changed, it would be another different substance.

A pure substance cannot be broken down into other simpler substances using physical methods.  Therefore, a pure substance has its own or defined characteristic properties.

Within the pure substances 2 types are distinguished: Elements and compounds.

regulation of gene expression. gene expression can be regulated by various cellular processes with the aim to control the amount and nature of the expressed genes. these regulatory proteins bind to dna and send signals that indirectly control the rate of gene expression

explanation:

ya the other dude is right