Page 1 of 116
CHEM 103 EXAM 1 (UNLV) EXAM QUESTIONS AND CORRECT
VERIFIED SOLUTIONS LATEST UPDATE THIS YEAR – JUST
RELEASED
CHEM 103 EXAM 1 (UNLV)
Exam Coverage
Matter, substances, mixtures, elements, compounds, atoms, and molecules
Physical states of matter and particle-level behavior
Physical properties, chemical properties, physical changes, and chemical changes
Homogeneous and heterogeneous mixtures and methods of classification
Atomic structure, subatomic particles, atomic number, mass number, and isotopes
Historical atomic models and major contributors to atomic theory
Periodic table organization, groups, periods, metals, nonmetals, and metalloids
Measurement, SI units, metric prefixes, density, temperature, and unit conversions
Significant figures, scientific notation, precision, accuracy, and measurement uncertainty
Chemical reasoning, calculations, classification, and application of foundational CHEM
103 concepts
1.
Which statement best describes matter according to the foundational concepts introduced in
CHEM 103?
A. Anything that produces heat when measured
B. Anything that has mass and occupies space
C. Anything that can be seen without a microscope
D. Anything capable of undergoing a chemical reaction
Answer: B
, Page 2 of 116
Rationale: Matter is defined as anything that has mass and occupies space, including solids,
liquids, gases, and substances that cannot be seen directly.
2.
What distinguishes a pure substance from a mixture when examining the composition of
matter?
A. A pure substance contains only one chemical identity, while a mixture contains multiple
substances
B. A pure substance must always be a solid at room temperature
C. A mixture cannot contain elements combined chemically
D. A pure substance must contain at least two different elements
Answer: A
Rationale: A pure substance has a constant composition and consists of one chemical
substance, whereas a mixture contains two or more substances physically combined.
3.
Which example represents an element rather than a compound or mixture?
A. Carbon dioxide
B. Salt water
C. Aluminum
D. Air
Answer: C
, Page 3 of 116
Rationale: Aluminum consists of only one type of atom and is therefore an element. Carbon
dioxide is a compound, while salt water and air are mixtures.
4.
Why is water classified as a compound rather than an element?
A. Water can exist as a solid, liquid, or gas
B. Water contains hydrogen and oxygen chemically combined in a fixed ratio
C. Water can be separated using filtration
D. Water has no measurable physical properties
Answer: B
Rationale: Water contains two different elements, hydrogen and oxygen, chemically bonded in
a definite proportion, making it a compound.
5.
Which characteristic is most directly associated with a solid state of matter?
A. Particles are widely separated and rapidly moving throughout a container
B. Particles have no attractive forces between them
C. Particles remain relatively close together and maintain a definite shape
D. Particles always move independently without restrictions
Answer: C
, Page 4 of 116
Rationale: Solid particles are closely packed and generally vibrate around relatively fixed
positions, giving solids definite shape and volume.
6.
How does a liquid differ from a solid under ordinary conditions?
A. A liquid has definite volume but assumes the shape of its container
B. A liquid has neither definite volume nor definite shape
C. A liquid has definite shape but no definite volume
D. A liquid contains no attractive forces between particles
Answer: A
Rationale: Liquids retain a definite volume but flow and therefore take the shape of their
container.
7.
Which description most accurately represents particles in a gas?
A. They are fixed in a rigid repeating arrangement
B. They are close together and vibrate around fixed positions
C. They are close together but cannot move past one another
D. They are relatively far apart and move freely throughout available space
Answer: D
CHEM 103 EXAM 1 (UNLV) EXAM QUESTIONS AND CORRECT
VERIFIED SOLUTIONS LATEST UPDATE THIS YEAR – JUST
RELEASED
CHEM 103 EXAM 1 (UNLV)
Exam Coverage
Matter, substances, mixtures, elements, compounds, atoms, and molecules
Physical states of matter and particle-level behavior
Physical properties, chemical properties, physical changes, and chemical changes
Homogeneous and heterogeneous mixtures and methods of classification
Atomic structure, subatomic particles, atomic number, mass number, and isotopes
Historical atomic models and major contributors to atomic theory
Periodic table organization, groups, periods, metals, nonmetals, and metalloids
Measurement, SI units, metric prefixes, density, temperature, and unit conversions
Significant figures, scientific notation, precision, accuracy, and measurement uncertainty
Chemical reasoning, calculations, classification, and application of foundational CHEM
103 concepts
1.
Which statement best describes matter according to the foundational concepts introduced in
CHEM 103?
A. Anything that produces heat when measured
B. Anything that has mass and occupies space
C. Anything that can be seen without a microscope
D. Anything capable of undergoing a chemical reaction
Answer: B
, Page 2 of 116
Rationale: Matter is defined as anything that has mass and occupies space, including solids,
liquids, gases, and substances that cannot be seen directly.
2.
What distinguishes a pure substance from a mixture when examining the composition of
matter?
A. A pure substance contains only one chemical identity, while a mixture contains multiple
substances
B. A pure substance must always be a solid at room temperature
C. A mixture cannot contain elements combined chemically
D. A pure substance must contain at least two different elements
Answer: A
Rationale: A pure substance has a constant composition and consists of one chemical
substance, whereas a mixture contains two or more substances physically combined.
3.
Which example represents an element rather than a compound or mixture?
A. Carbon dioxide
B. Salt water
C. Aluminum
D. Air
Answer: C
, Page 3 of 116
Rationale: Aluminum consists of only one type of atom and is therefore an element. Carbon
dioxide is a compound, while salt water and air are mixtures.
4.
Why is water classified as a compound rather than an element?
A. Water can exist as a solid, liquid, or gas
B. Water contains hydrogen and oxygen chemically combined in a fixed ratio
C. Water can be separated using filtration
D. Water has no measurable physical properties
Answer: B
Rationale: Water contains two different elements, hydrogen and oxygen, chemically bonded in
a definite proportion, making it a compound.
5.
Which characteristic is most directly associated with a solid state of matter?
A. Particles are widely separated and rapidly moving throughout a container
B. Particles have no attractive forces between them
C. Particles remain relatively close together and maintain a definite shape
D. Particles always move independently without restrictions
Answer: C
, Page 4 of 116
Rationale: Solid particles are closely packed and generally vibrate around relatively fixed
positions, giving solids definite shape and volume.
6.
How does a liquid differ from a solid under ordinary conditions?
A. A liquid has definite volume but assumes the shape of its container
B. A liquid has neither definite volume nor definite shape
C. A liquid has definite shape but no definite volume
D. A liquid contains no attractive forces between particles
Answer: A
Rationale: Liquids retain a definite volume but flow and therefore take the shape of their
container.
7.
Which description most accurately represents particles in a gas?
A. They are fixed in a rigid repeating arrangement
B. They are close together and vibrate around fixed positions
C. They are close together but cannot move past one another
D. They are relatively far apart and move freely throughout available space
Answer: D
