The fizzing of soda is a physical change that involves the release of gaseous carbon dioxide. During fizzing of a soda, you can see bubbles of carbon dioxide in the soda rise to the top. A bottle of soda doesn’t fizz when it is closed because the pressure is higher, and keeps the carbon dioxide dissolved in the liquid.

Melting is an example of a physical change. A physical change is a change to a sample of matter in which some properties of the material change, but the identity of the matter does not.

Baking a cake is a chemical change because the baking powder or baking soda will undergo a chemical reaction. The heat helps baking powder or soda produce tiny bubbles of gas which makes the cake light and fluffy. That’s why chemical reactions are involved in baking a cake.

The following that is not true about chemical changes is “They can be reversed by physical changes.”, the answer is letter B. A chemical change can form a new substance, can be detected by the change in color and they have properties different from their starting materials.

All chemical changes are irreversible changes. Once the chemical properties of a substance are changed, it becomes another substance. Thus, it cannot return to its original state.

With a physical change, a substance changes form, but does not transform into a different substance. Many physical changes can be reversed, like water freezing to form ice. With a chemical change, a substance transforms into a different substance. Most chemical changes are irreversible.

Matter is composed of atoms and molecules and is always changing its form by either physical or chemical changes. The Law of Conservation of Mass states that mass is neither created nor destroyed during any physical or chemical changes.