Referring to the attached picture, transitions 1, 2 and 4 are chemical changes, whereas transitions 3 and 5 are physical changes.
Physical changes are those in which the identity of the substance is not modified, whereas in chemical changes, chemical reactions produce new substances.
Let's consider the attached image in which we have two elements: Blue (B) and Red (R).
In transition 1, the following reaction is verified.
B₂ + R₂ ⇒ BR + B₂
A new substance (BR) has been formed, so this is a chemical change.
In transition 2, the following reaction is verified.
BR + B₂ ⇒ B₂R
A new substance (B₂R) has been formed, so this is a chemical change.
In transition 3, BR and B₂ are separated from each other. But the molecules remain the same. Thus, this is a physical change.
In transition 4, the following reaction is verified.
B₂ ⇒ 2 B
A new substance (B) has been formed, so this is a chemical change.
In transition 5, molecules are closer but their identity doesn´t change. Thus, this is a physical change.
Referring to the attached picture, transitions 1, 2 and 4 are chemical changes, whereas transitions 3 and 5 are physical changes.
You can learn more about physical and chemical changes here: https://brainly.com/question/13620149
