All other elements react with other elements to form compounds. In the special case where the reaction produces fixed numbers of the same types of atoms in exactly the same configuration, we say the elements have formed a molecule.
Answer:
a
Explanation:
the answer is a i'm pretty sure it might be wrong tho i'm sorry
The correct answer for this question would be option B. The common name of the group whose members are characterized by endoskeleton and a unique water vascular system are called the <span> Echinoderms. Examples of echinoderms are starfish, sea urchin, feather stars and sea cucumbers. Hope this is the answer that you are looking for.</span>
C) and d) are physical changes while b) is chemical
