Complete the sentence.
A piece of avocado turning brown is a ().
physical change chemical change
Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Burning a piece of paper is a chemical change. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
Cutting a piece of paper is a physical change. The cut pieces are still made of paper.
A change of state is a type of physical change. For example, ice melting is a physical change. Ice and liquid water are made of the same type of matter: water.
A piece of avocado turning brown is a chemical change. The avocado reacts with oxygen in the air to form a different type of matter.
If you scrape off the brown part of the avocado, the inside will still be green. The inside hasn't touched the air. So the chemical change hasn't happened to that part of the avocado.