Horizon International School
C C
hemistry
ompetition
Answer key
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Answer
Question
Answer
Name:_________________Grade 7
1
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. What equation would you use to find the volume of a rectangular box?
a. volume = length  width  height
c. volume = length  width
b. volume = length + width + height
d. volume = length + height
____
2. Which of the following units would you use to express the volume of an irregular solid such as a rock?
a. liters (L)
c. milliliters (mL)
b. cubic centimeters (cm3)
d. newtons (N)
____
3. Which of the following is NOT an example of a physical change?
a. the shaping of a gold bar
c. the explosion of fireworks
b. the melting of a Popsicle
d. the sanding of a piece of wood
____
4. What kinds of changes in substances are always physical changes?
a. changes of state from solid to liquid to gas and back
b. changes that result in new substances being formed
c. changes that change the identity of the substance
d. changes that change the density of the substances
____
5. Why are chemical properties harder to observe than physical properties?
a. Chemical properties change the substance’s identity.
b. Chemical properties depend on the size of the sample.
c. Physical properties can be observed and measured.
d. Physical properties change the identity of a substance.
____
6. Which of the following is NOT the result of a chemical change?
a. soured milk
c. ground flour
b. rusted metal
d. digested food
____
7. Which of the following is a chemical property of matter?
a. solubility
c. density
b. volume
d. reactivity
____
8. In a graduated cylinder containing several liquid layers, the least dense liquid is found
a. floating at the top.
c. in the lightest colored layer.
b. in the middle layer.
d. settled on the bottom.
____
9. How does a physical change differ from a chemical change?
a. In a physical change new volumes are created.
b. In a physical change new materials are produced.
c. In a physical change the composition is unchanged.
d. In a physical change the change is reversible.
____ 10. Which of the following events is NOT a common sign that a chemical change has taken place?
a. change in color or odor
c. foaming or bubbling
b. change in state
d. production of heat or light
____ 11. What chemical property is responsible for iron rusting?
a. flammability
c. nonflammability
b. conductivity
d. reactivity with oxygen
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____ 12. What unit of density would be appropriate to describe a solid bar of silver?
a. g/mL
c. oz/ft3
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b. g/cm
d. kg/L
____ 13. Which physical property of matter describes the relationship between mass and volume?
a. density
c. reactivity
b. ductility
d. weight
____ 14. Malleability is an example of a
a. physical property.
b. physical change.
c. chemical property.
d. chemical change.
____ 15. In scientific experiments, the amount of a liquid used is expressed in
a. centimeters or meters
c. liters or milliliters
b. grams or milligrams
d. ounces or gallons
____ 16. How could you change the mass of an object?
a. Move to another large body or moon.
b. Add or take away some matter.
c. Make Earth spin faster or slower.
d. Change the object’s temperature.
____ 17. Why is freezing water to make ice considered a physical change?
a. The ice has some new properties.
c. The water changes its state.
b. The ice floats on water.
d. The water changes its identity
____ 18. In a solid, the particles
a. overcome the strong attraction between them.
b. vibrate in place.
c. slide past one another.
d. move independently of one another.
____ 19. A gas
a. has a definite volume but no definite shape.
b. has a definite shape but no definite volume.
c. has fast-moving particles.
d. has particles that are always close together.
____ 20. At higher temperatures
a. particles in an object move faster.
b. gas particles bump into walls less often.
c. a gas contracts.
d. particles in an object have less energy.
____ 21. The reverse of condensation is
a. boiling.
b. evaporation.
c. freezing.
d. sublimation.
____ 22. Which of the following will NOT break down compounds?
a. heat
c. a chemical change
b. electric current
d. filtering
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____ 23. How do elements join to form compounds?
a. randomly
b. in a specific mass ratio
c. in a ratio of 1 to 8
d. as the scientist plans it
____ 24. What is a pure substance made of two or more elements that are chemically combined?
a. element
c. mixture
b. compound
d. solution
____ 25. If a spoonful of salt is mixed in a glass of water, what is the water called?
a. solute
c. solvent
b. solution
d. element
____ 26 . How can a compound be broken down?
a. by physical changes
b. by chemical changes
c. by crushing
d. by cooling
____ 27. What forms when particles of two or more substances are evenly mixed?
a. compound
c. solution
b. suspension
d. element
____ 28. Which of the following is NOT true of compounds?
a. They contain two or more elements.
b. They form after a physical change.
c. They have their own physical properties.
d. They do not form randomly.
____ 29. How would you describe the nucleus?
a. dense, positively charged
b. large, positively charged
c. tiny, negatively charged
d. dense, negatively charged
____ 30. What is the charge of an aluminum ion that has 13 protons and 10 electrons?
a. 1+
c. 3+
b. 2+
d. 3–
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