Chemical changes that involve gas production are most likely to involve bubbling or an odor.

Here's why:

* Bubbling: When a gas is produced during a chemical reaction, it will often escape from the liquid or solid mixture as bubbles. This is because gases have lower density than liquids and solids.

* Odor: Many gases have distinct smells. Even if the initial reactants don't have a strong smell, the product gas might be quite noticeable.

Examples of chemical changes involving bubbling and/or odor:

* Baking soda and vinegar: The reaction between baking soda (sodium bicarbonate) and vinegar (acetic acid) produces carbon dioxide gas, which causes bubbling.

* Decomposition of hydrogen peroxide: Hydrogen peroxide decomposes into water and oxygen gas. You can see bubbles of oxygen form, and the reaction might have a slight odor of bleach.

* Burning: Combustion reactions often produce gases like carbon dioxide and water vapor, which can result in both bubbling and odor.

Important Note: Not all chemical changes involve bubbling or odor. Some reactions might involve color changes, precipitation (formation of a solid), or changes in temperature without producing any gases.