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7th Science Chap 2 Test

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 1. 
Which of the following does NOT describe elements?
a.
have particles that are all alike
b.
can be broken down into simpler substances
c.
have unique sets of properties
d.
can join together to form compounds
 

 2. 
An element that conducts thermal energy well and is easily shaped is a
a.
metal.
c.
nonmetal.
b.
metalloid.
d.
None of the above
 

 3. 
In which classification of matter are the components chemically combined?
a.
alloy
c.
compound
b.
colloid
d.
suspension
 

 4. 
How is a mixture different from a compound?
a.
Mixtures have two or more components.
b.
Each substance in a mixture keeps its original properties.
c.
Mixtures are commonly found in nature.
d.
Solids, liquids, and gases can form mixtures.
 

 5. 
The particles in both a suspension and a colloid can
a.
scatter light.
c.
be soluble.
b.
settle out.
d.
pass through a fine filter.
 

 6. 
When elements form compounds, the elements
a.
keep their original properties.
b.
react to form a new substance with new properties.
c.
combine in a random fashion.
d.
have the same properties as the compound.
 

 7. 
Which of the following does not describe elements?
a.
They can combine to form compounds.
b.
They have unique sets of properties.
c.
They can be broken down into simpler substances.
d.
All the particles are alike.
 

 8. 
Although a meteorite might travel millions of kilometers to reach Earth, the particles of iron in a meteorite are identical to the particles of iron in an iron skillet because iron is a
a.
metalloid.
c.
colloid.
b.
pure substance.
d.
compound.
 

 9. 
The three major categories of elements are
a.
pure substances, compounds, and mixtures.
b.
alloys, suspensions, and colloids.
c.
solutions, colloids, and suspensions.
d.
metals, nonmetals, and metalloids.
 

 10. 
Nonmetals are
a.
good conductors of thermal energy.
c.
ductile.
b.
unmalleable.
d.
None of the above
 

 11. 
Which of the following is NOT a compound?
a.
water
c.
gold
b.
ammonia
d.
salt
 

 12. 
Which of the following describes compounds?
a.
have the same characteristic properties as the elements that form them
b.
are composed of elements that join in a specific ratio according to their masses
c.
are composed of two or more elements that are physically combined
d.
are random combinations of elements
 

 13. 
In nature, the element ____ is needed to make proteins.
a.
nitrogen
c.
neon
b.
aluminum
d.
sodium
 

 14. 
Which of the following describes a mixture?
a.
formed from two or more substances chemically combined
b.
made up of two or more substances joined in a specific ratio
c.
made up of two or more substances that keep their identities
d.
can be separated only by chemical means
 

 15. 
____ is used to separate water into hydrogen and oxygen.
a.
Distillation
c.
Filtration
b.
Electrolysis
d.
Chromatography
 

 16. 
A ____ can be used to separate a powdered mixture of the elements iron and aluminum.
a.
centrifuge
c.
heat source
b.
magnet
d.
filter
 

 17. 
A ____ is used by medical labs to separate heavier blood cells from liquid plasma.
a.
centrifuge
c.
heat source
b.
magnet
d.
filter
 

 18. 
Which of the following is a mixture?
a.
carbon dioxide
c.
air
b.
sodium chloride
d.
ammonia
 

 19. 
Which of the following is often called the universal solvent?
a.
sodium
c.
vinegar
b.
air
d.
water
 

 20. 
Blood is a(n)
a.
element.
c.
alloy.
b.
compound.
d.
suspension.
 

 21. 
You have a sample of an unknown clear liquid. Light passes through the sample and, after testing the sample, you know that its particles do not separate in a centrifuge. The sample is most likely a(n)
a.
alloy.
c.
solution.
b.
colloid.
d.
suspension.
 

 22. 
An unknown sample scatters light and is separated by a filter. The sample is most likely a(n)
a.
compound.
c.
suspension.
b.
solution.
d.
an element.
 

 23. 
An unknown sample scatters light and passes through a filter without leaving a residue. The sample is most likely a
a.
compound.
c.
suspension.
b.
solution.
d.
colloid.
 

 24. 
When mixed with other elements, ____ can become good conductors.
a.
nonmetals
c.
suspensions
b.
metalloids
d.
colloids
 

 25. 
Which of the following is an element?
a.
sodium chloride
c.
sodium hydroxide
b.
sodium
d.
sodium sulfate
 

 26. 
Which of the following is a compound?
a.
nitrogen
c.
carbon dioxide
b.
oxygen
d.
hydrogen
 

 27. 
Medicines that instruct you to shake the bottle well before use are most likely
a.
solutions.
c.
suspensions.
b.
alloys.
d.
colloids.
 

 28. 
An 18 g sample of water can be broken down into 2 g of hydrogen and 16 g of oxygen. What is the mass ratio of hydrogen to oxygen in water?
a.
1:8
c.
3:4
b.
8:1
d.
3:8
 

 29. 
A solution that contains less solute than it can hold at a given temperature is
a.
saturated.
c.
concentrated.
b.
unsaturated.
d.
supersaturated.
 

 30. 
Which of the following does NOT usually increase the speed at which a solid dissolves?
a.
mixing by stirring or shaking
c.
crushing the solute
b.
heating
d.
adding ice
 

 31. 
Sodium is a soft, silvery metal that reacts violently with water. Chlorine is a poisonous, greenish yellow gas. When you combine these two elements, you form a soluble white solid that is soluble in water and safe to eat. This illustrates that
a.
a compound has different properties from the elements that form it.
b.
a compound has the same properties as the elements that form it.
c.
a mixture has different properties from the elements that form it.
d.
a mixture has the same properties as the elements that form it.
 

Completion
Complete each sentence or statement.
 

 32. 
Elements that are brittle and are poor conductors are ____________________.
 

 

 33. 
The substance that dissolves to form a solution is the ____________________.
 

 

 34. 
A ____________________ is a pure substance composed of two or more elements that are chemically combined. (compound or mixture)
 

 

 35. 
If a spoonful of salt is mixed in a glass of water, the salt is the _____________________. (solvent or solute)
 

 

 36. 
____________________ are solid solutions of metals or nonmetals dissolved in metals. (Alloys or Metalloids)
 

 

 37. 
A colloid has properties of both solutions and ____________________. (suspensions or solvents)
 

 

 38. 
A ____________________ is composed of particles of two or more substances that are distributed evenly among each other. (solution or suspension)
 

 

 39. 
A(n) ____________________ is a pure substance that cannot be separated into simpler substances by physical or chemical means.
 

 

 40. 
A(n) ____________________ is a substance in which there is only one type of particle.
 

 

 41. 
____________________ are elements that are shiny and are good conductors of thermal energy and electric current.
 

 

 42. 
____________________ are elements that are poor conductors of thermal energy and electric current.
 

 

 43. 
____________________ are also called semiconductors.
 

 

 44. 
A(n) ____________________ is a combination of two or more substances that are not chemically combined.
 

 

 45. 
A(n) ____________________ is a machine that separates mixtures according to the densities of the components.
 

 

 46. 
The process in which particles of substances separate and spread evenly throughout a mixture is known as ____________________.
 

 

 47. 
A(n) ____________________ is a substance in which a solute is dissolved.
 

 

 48. 
A(n) ____________________ solution contains less solute than a concentrated solution.
 

 

 49. 
A solution that contains all the solute it can hold at a given temperature is said to be ____________________.
 

 

 50. 
____________________ is the process of using electric current to break compounds into simpler compounds and elements.
 

 



 
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