Chemistry 105 Practice Test: Answer Key

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Chem 105
Practice Test 1
Note: There will not be this many questions on your test, I just wanted to give you as much practice as possible. Also, none of these exact questions will be on the test, just similar questions. Also, make sure you can do the homework, as I may have some questions similar to the homework questions.

1.Molecules can be described as
a.a mixture of two or more pure substances.
b.a mixture of two or more elements that has a specific ratio between components. c.two or more atoms chemically joined together.
d.a heterogeneous mixture
e.a homogeneous mixture
Answer: C

2.Dalton's Atomic Theory states
a.that all elements have several isotopes.
b.that matter is composed of small indestructible particles. c.that the properties of matter are determined by the properties of atoms. d.that energy is neither created nor destroyed during a chemical reaction. e.that an atom is predominantly empty space.

Answer: B

3.Which of the following represents a hypothesis?
a.Sodium reacts with water to form sodium hydroxide and hydrogen gas. b.Nitrogen gas is a fairly inert substance.
c.Nickel has a silvery sheen.
d.When a substance combusts, it combines with air.
e.When wood burns, heat is given off.
Answer: D

4.Which is true of a Scientific Theory (circle all that apply) a.It is an interpretation for an observation
b.It is a general explanation for the manifestation and behavior of all nature c.It can be validated or invalidated by experiment and observation d.It describes why things happen
Answer: B, C, and D

5.Mass (circle all that apply)
a.Is dependent on location (gravity)
b.Is the amount of matter in a substance and remains the same regardless of location c.can be measured by using a scale or balance measured in ml
Answer: B and C

6.The states of matter are
a.Solid and gas
b.Liquid and gas
c.Gas, solid, and liquid
d.Gas, air, and vapor
Answer: C

7.A liquid (circle all that apply)
a.Has a definite volume
b.Has particles that are less orderly and can move about freely c.Has particles that are tightly packed
d.Has no definite volume or shape
e.Answer: A and B

8. Identify dry ice as a solid, liquid, or gas.
d.both solid and liquid
Answer: A

9.When a gas is cooled (circle all that apply)
a.Its molecules have fewer energetic collisions
b.The motion of the gas particles decrease
c.The motion of gas particles increase
d.Nothing happens to the gas particles
Answer: A and B

10.Classify each of the following as a mixture or a pure substance: a.Carbon dioxide _____________________
b.Blood ______________________
c.Helium (He) ______________________
d.Sugar water _______________________
Answer: A-pure substance; B-mixture; C-pure substance; D-mixture

11.Choose the pure substance from the list below.
a.sea water
Answer: B

12.Choose the heterogeneous mixture from the list below.
b.chlorine gas coffee
d.chicken noodle soup
e.carbon (graphite)
Answer: D

13.Which of the following statements about crystalline and amorphous solids is TRUE? a.A crystalline solid is composed of atoms or molecules arranged with long-range repeating order. b.An example of a crystalline solid is glass.

c.An example of an amorphous solid is table salt (NaCl).
d.An amorphous solid is composed of atoms or molecules with a majority of its volume empty. e.All of the above statements are TRUE.
Answer: A

14.A substance that can't be chemically broken down into simpler substances is considered to be a.a homogeneous mixture. element.
c.a heterogeneous mixture.
d.a compound. electron.
Answer: B
15.Two or more substances in variable proportions, where the composition is constant throughout are considered a.a compound. element.
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