Copernicus should be the topic, and the central idea should be how he came up with the heliocentric theory. I hope I helped, please tell me if I am incorrect or if you need more help!
Answer:
In its stable molecular form, oxygen exists as two atoms and is written O2. to distinguish it from an atom of oxygen O, or ozone, a molecule of three oxygen atoms, O3. Even though each of these is all oxygen, combining atoms of the same element may give very different properties to the molecule.
Explanation:
A noun is a person, place, or thing. The nouns in this sentence are the people, the places, and the things, meaning the answer is D. Boy and girl are people, school is a place, and hands are things.
