The smallest unit into which a compound can be divided and still be that same compound is a(n)

An empty fuel tank can still contain and therefore can be even more dangerous than one full of liquid fuel.

How have the greenhouse gasses increased from the year 2000 to 2018

Which of the following is a physical change? a. burning a piece of wood b. sawing a piece of wood in half c. rust forming on an iron fence d. a copper roof changing color from orange to green