what ate chemical and physical changes class 9 cbse
Answers
Explanation:
Learning Objective
Identify the key features of physical and chemical changes
Key Points
Physical changes only change the appearance of a substance, not its chemical composition.
Chemical changes cause a substance to change into an entirely substance with a new chemical formula.
Chemical changes are also known as chemical reactions. The “ingredients” of a reaction are called reactants, and the end results are called products.
Terms
chemical changeA process that causes a substance to change into a new substance with a new chemical formula.
chemical reactionA process involving the breaking or making of interatomic bonds and the transformation of a substance (or substances) into another.
physical changeA process that does not cause a substance to become a fundamentally different substance.
Answer:
A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.
A chemical change happens when one chemical substance is transformed into one or more different substances, such as when iron becomes rust. Chemical changes occur through the process of chemical reactions, and the resulting substances have different properties because their atoms and molecules are arranged differently.