8th grade integrated science Assessment Standard 1, objective 2
Multiple Choice
a1. An ice cube is left on a table for an hour. What evidence shows a physical change takes place?
A. It turns into a different substance.
B. It gives off carbon dioxide
C. It melts into water
D. It bubbles and gives off gas
a2. Salt is mixed with water and stirred. Is this a physical or chemical change?
A. It is chemical because a new substance, saltwater, has been formed.
B. It is chemical because a gas, water vapor, is given off.
C. It is physical because the salt has turned into a gas.
D. It is physical because it is easily reversible.
a3. A balloon is placed in a freezer and left overnight. Which would be evidence that a physical change occurred when the freezer was opened the next day? The balloon
A. cannot return to it’s original shape
B. has shrunk in size
C. cannot be found
D. is giving off a new gas
b4. An iron nail left outdoors for a year undergoes a chemical change. What evidence would visible? The nail would be
A. bent
B. rusty
C. buried in soil
D. sharper
b5. What hazards exist when mixing unknown chemicals?
A. A physical change may make them less useful
B. A physical change may make them change phase.
C. A chemical change may create heat and expansion.
D. A chemical change may alter the colors.
Use the following data to answer the next two questions.
An experiment with rock salt used three beakers. Each had 100 ml of water and 25 g of salt added. Beaker A was left alone and Beaker B and C were changed. The time needed to dissolve the salt was measured.
Beaker | Change | Time to dissolve |
A | None | 6 hours (360 minutes) |
B | Stirred with spoon | 8 minutes |
C | Heated on hot plate | 25 minutes |
b6. Which of the following is the best question for this experiment?
A. What happens when you place 25 grams of salt into 100 mL of water?
B. What changes the speed it takes salt to dissolve?
C. What happens to salt when it dissolves in water?
D. When does salt and water change chemically?
b7. Which conclusion best sums up this experiment?
A. Salt will dissolve in water if left alone.
B. Heating and stirring are equally important if you want to dissolve salt.
C. Salt will dissolve in water quickly if the size of the salt particles is smaller.
D. Salt will dissolve more quickly if it is stirred than if it is heated or left alone.
- A student puts out fire on the stove by dumping baking soda on the flame. How has the student used scientific knowledge in his daily life?
A. He knew a physical property of baking soda is that it doesn’t melt
B. He knew a chemical property of baking soda is that it doesn’t burn
C. He knew a chemical property of baking soda is that it dissolves in water
D. He knew a physical property of baking soda is that it is white in color
b9. How do you know when a chemical reaction has occurred?
A. a new substance has formed; it would be hard to reverse
B. a phase change has occurred and heat was given off.
C. the substance changes size, shape, texture and mass
D. the mass of the reactants is changed into energy that is given off
Use this information to answer the next two questions.
Reactions Involving Atmospheric Oxygen
Reaction | Speed-measured in | Reactants | Products |
Rust | Months | Metal, often water | Rust |
Fire | Minutes | Fuel (carbon compounds) | Carbon dioxide, water |
Respiration | Hours | Food (carbon compounds) | Carbon dioxide, water |
Photosynthesis | Hours | Carbon dioxide, water | Sugar, oxygen |
c10. What is the main difference between fire and respiration?
A. how quickly they happen
B. the fuels that are burned
C. the products
D. they are identical
c11. How is rust different from the other three reactions?
A. It happens in the out-of-doors.
B. It uses water.
C. It involves metals.
D. It cannot be measured.
- Scientists have developed special paints for the undersides of ships at sea. What problem are they trying to correct?
A. flexibility of steel beams
B. dissolving of plastic parts
C. rusting of metal parts
D. melting of ship engines
c13. How does a burning fire consume atmospheric oxygen differently than a nail rusting?
A. A fire uses oxygen much more rapidly
B. Rusting requires a special form of oxygen
C. A fire does not need as much oxygen as rusting
D. Rusting is a chemical change, fire is not
d14. Charles Goodyear accidentally spilled sulfur on latex rubber and discovered a way to make the rubber more elastic. What does his discovery show about science?
A. scientific discoveries are made in many ways.
B. chemical changes use the same set of steps and procedures
C. physical changes are random and unpredictable
D. scientific discoveries are made following specific steps.
d15. A chemical change occurs when an egg cooks. What effect does the chemical change have on the physical properties of the egg?
A. the egg is unchanged.
B. the egg has new physical properties
C. the egg cannot be measured
D. the egg has doubled in size.
d16. An iron nail rusts when left outdoors. Why might the nail no longer be useful?
A. it has turned orange and red
B. it has become wet and dry several times
C. it is now made of a softer substance
D. it is not long and skinny any more.
Essay
1. Describe two ways you know that cooking an egg (or most other foods) results in a chemical change.
2. What are two differences between chemical and physical changes?
Answers:
1. C
2. D
3. B
4. B
5. C
6. C
7. D
8. B
9. A
10. A
11. C
12. A
13. A
14. B
15. C
Sample Essay Answers
1. The food changes color, consistency, and it can burn which creates a new substance. Cooking creates smells and requires a change of energy that are both evidence for chemical change.
2. Chemical changes create new substances, are hard to reverse, and may give off light, heat or odor. Physical changes do not create new substances, are reversible and often involve a change of shape or phase.