Physical change

A Physical changes is a change that affects the form of the chemical substance, but not it's chemical composition.

A Chemical change is a change that ends up being a totally new chemical substance.

Chemical change

Fire is a chemical change because, a substance combined with oxygen can cause a fire.

Popcorn is a Physical change because when the kernel is cooking, water that is inside the kernel is changed to steam and cause pressure against the insides of the kernel causing it to pop and become popcorn.

Bread becoming toast is a chemical change because you have added heat to the bread to make it into toast... But your toast can't ever become bread again.

When heat is applied to ice, it causes the ice to melt and become water... If we add heat to water, the water then becomes gas, if we cool down gas, it becomes water again and so on, this is a physical change