Observing Chemical Changes

1. Which of the following is true about chemical reactions?

• a. They are accompanied by changes in energy.

• b. They form new substances with new properties.

• both a and b

• neither a nor b

2. In an endothermic reaction, energy is

• a. absorbed

• b. released

• c. converted to mass

• d. synthesized

3. Which of the following is NOT a physical property?

• a. melting point

• b. state of matter

• c. density

• d. flammability

4. Substances formed as a result of a chemical reaction are called

• a. catalysts

• b. precipitates

• c. products

• d. reactants

5. In an exothermic reaction, energy is

• a. absorbed

• b. released

• c. converted to mass

• d. synthesuzed

6. What types of reactions best describe what is shown in a fireworks display?

• a. chemical and endothermic

• b. chemical and exothermic

• c. physical and endothermic

• d. physical and exothermic

7. What types of reactions best describe a refrigerated egg being cracked and then cooked in a heated pan?

• a. chemical and endothermic

• b. chemical and exothermic

• c. physical and endothermic

• d. physical and exothermic

8. Regan pulled a calf muscle during the 400-meter race at Saturday's track meet. Coach Hohl used an instant cold pack to give her relief. The instant cold pack is a good example of an endothermic reaction. Why?

• a. The chemicals inside absorb heat energy from their surroundings.

• b. The reaction feels cold.

• c. both a and b

• d. neither a nor b

9. Which of the following results in a chemical change in matter?

• a. bending a straw

• b. braiding hair

• c. boiling water

• d. burning wood

10. A solid that forms from LIQUIDS in a chemical reaction is called a

• a. catalyst

• b. precipitate

• c. lumpy clumpy

• d. reactant