Question

read the following sentences from the section \chemical reaction definition.\
contrast this with a physical change, where the appearance is altered, but the molecular structure is unchanged, or a nuclear reaction, in which the composition of the atomic nucleus changes.
in a chemical reaction, the atomic nucleus is untouched, but electrons may be transferred or shared to break and form chemical bonds.
which answer choice best describes how the sentences help to develop a central idea of the article?s?
they both show that chemical reactions do have some features in common with physical reaction
they both help to clarify what a chemical reaction is by distinguishing it from other types of reactions.
they both demonstrate that nuclear reactions are a more advanced type of chemical reaction.
they both emphasize the idea that it is difficult to see a chemical reaction with your own eyes.

Explanation:

The sentences define chemical reactions by contrasting them with physical and nuclear reactions, highlighting the unique features of chemical reactions (electron transfer/sharing, untouched nucleus) against the others. This directly clarifies what a chemical reaction is by setting it apart from similar reaction types.

Answer:

They both help to clarify what a chemical reaction is by distinguishing it from other types of reactions.