Complete the sentence.
In this chemical reaction, oxygen is a ().

 - product
 - reactant
Read the underlined text carefully. Look for information about what happens to oxygen in this chemical reaction.
Hydrogen peroxide, a household disinfectant, breaks down into water and oxygen gas over time. Light speeds up this process, so hydrogen peroxide is typically stored in a dark-colored bottle. The bottle's dark coloring blocks light and makes the hydrogen peroxide last longer.
The underlined text tells you that oxygen forms when hydrogen peroxide breaks down. Because oxygen is produced by this chemical reaction, oxygen is a product.