Stirring dry yeast into a bowl of hydrogen peroxide
causes bubbles to form. Blowing air into a glass of milk
with a straw also causes bubbles to form. One of these is
a physical change, and the other is a chemical change.

If the reaction is a chemical change, new substances with different properties and identities are formed. This may be indicated by the production of an odor, a change in color or energy, or the formation of a solid.

answer; (d) all matter is composed of small particles, which combine to make larger objects;