chemical and physical changes

Question 1

When do physical changes occur?

Give examples:

Answer 1

Physical changes occur when the appearance of a substance is changed without changing its nature. some examples of physical changes are:

Cutting a material
dissolution
change shape
phase changes

Question 2

when do chemical changes take place?

Examples:

Answer 2

Chemical changes take place when two or more substances, called reactants, interact to create new substances called products. Some signs of a chemical change are:

Change nature of substance
presence of a gas (bubbles, smell)
light, heat or electricity produced
irreversible
change in colour