Answer:
the study of the structure, reaction, and composition of different kinds of substances
Explanation:

Our health is crucial when it comes to the environment. The environment can affect our health through physical, internal, and chemical factors. For example, if the environment is extremely polluted, us humans would get sick easily and there would be many birth defects.
What makes u think that? Who told u that? Ur the only person who gets to decide that for urself I’m sure ur a great person. Change your mindset !