Question

the oxygen (o₂) this reaction produces exists as a gas. which part of the video sergio watched provides evidence to support this? a increase in temperature b bubbles forming as foam c creating a mixture using food coloring d transferring hydrogen peroxide to the flask

Explanation:

When a gas is produced in a reaction, one of the common visual evidences is the formation of bubbles. Bubbles forming as foam indicate the release of a gas (in this case, oxygen). An increase in temperature (A) could be due to an exothermic reaction but not specific to gas production. Creating a mixture using food coloring (C) is about mixing substances, not gas production. Transferring hydrogen peroxide to the flask (D) is just a step in setting up the reaction, not evidence of gas production.

Answer:

B. bubbles forming as foam