Which of these is not a sign of a chemical reaction?

• A gas is given off.

• The material dissolves.

• Heat is released.

• A color change occurs.

The substance that is formed in a chemical reaction is called the

• polymer

• reactant

• radical

• product

Which of the following stores chemical energy?

• the temperature of a substance

• the density of a substance

• the bonds of a molecule

• the nucleus of an atom

Which of the following occurs in an endothermic reaction but not in an exothermic reaction?

• Chemical bonds are broken.

• Energy is absorbed.

• Molecules are formed.

• Atoms are rearranged.

A type of reaction that produces an increase in temperature is

• endothermic

• exothermic

• covalent

• nonpolar

An example of an endothermic reaction is

• bioluminescence by a firefly

• an exploding firecracker

• burning gasoline

• photosynthesis by a plant

A reaction in which the products contain more chemical energy than the reactants is

• exothermic

• electrical

• endothermic

• exergonic

Which of these represents the release of chemical energy?

• pouring gasoline into a tank

• burning charcoal in a grill

• a toy car running down a ramp

• warming food in a microwave

Which of the following are the products and reactants of a chemical reaction most likely to have in common?

• atoms

• molecules

• physical properties

• chemical properties

Which of the following occurs when gasoline is burned?

• New elements are formed.

• New atoms are formed.

• New molecules are formed.

• All of the above