WHat is the key difference between physical and chemical change?

What are some of the ways you can tell a nwew substance is formed?

Physical change that produce gas?

How do you determine the properties of a substance?

What happens in a chemical change?

Chemical reaction?

Difference between chemical reaction and change?

Combustion?

Example of combustion?

WHat is one of the most useful uses of combustions for humans?

Photosynthesis

Respiration?

Why do we get exhausted after a long exercising session?

Chemical Weathering

Flammable substances?

Corrosion