Question

which of these is an example of a chemical change?
all of these
a piece of wood burning in a campfire
baking soda reacting with vinegar, causing bubbles and foam
an iron rusting when exposed to the air

Explanation:

A chemical change results in the formation of new substances. Wood burning produces carbon - dioxide and other substances. Baking soda reacting with vinegar forms carbon - dioxide gas and other compounds. Iron rusting forms iron oxide. All are chemical changes.

Answer:

A. All of these