200+ QUESTIONS & ANSWERS WITH
RATIONALES
,WGU D425 Intro to Chemistry (2026/2027)
Question 1
Which statement best describes matter?
A. Anything that produces energy
B. Anything that has mass and occupies space
C. Anything that can undergo combustion
D. Anything visible to the human eye
Answer: B
Rationale: Matter is defined as anything that has mass and occupies space. Matter can exist as
solids, liquids, gases, and other states.
Question 2
Which of the following is an example of a chemical property?
A. Density
B. Melting point
C. Flammability
D. Boiling point
Answer: C
Rationale: Flammability describes a substance's ability to undergo a chemical reaction with
oxygen. Melting point, boiling point, and density are physical properties.
Question 3
Which change is a physical change?
A. Iron rusting
B. Wood burning
,C. Ice melting
D. Gasoline combusting
Answer: C
Rationale: Melting changes water from solid to liquid without changing its chemical identity.
Rusting, burning wood, and combustion produce new substances.
Question 4
Which particle determines the identity of an element?
A. Neutron
B. Electron
C. Proton
D. Isotope
Answer: C
Rationale: The number of protons in an atom is its atomic number and uniquely identifies the
element.
Question 5
An atom contains 17 protons, 18 neutrons, and 17 electrons. What is its mass number?
A. 17
B. 18
C. 34
D. 35
Answer: D
Rationale: Mass number = protons + neutrons. Therefore, 17 + 18 = 35.
, Question 6
An atom with 11 protons and 10 electrons has what charge?
A. −1
B. 0
C. +1
D. +2
Answer: C
Rationale: The atom has one more positive proton than negative electron: 11 − 10 = +1.
Question 7
Which particle has a negative electrical charge?
A. Proton
B. Neutron
C. Electron
D. Nucleus
Answer: C
Rationale: Electrons carry a negative charge, protons are positive, and neutrons have no net
charge.
Question 8
What does the atomic number of an element represent?
A. Number of neutrons
B. Number of protons
C. Number of protons plus neutrons
D. Number of valence electrons
RATIONALES
,WGU D425 Intro to Chemistry (2026/2027)
Question 1
Which statement best describes matter?
A. Anything that produces energy
B. Anything that has mass and occupies space
C. Anything that can undergo combustion
D. Anything visible to the human eye
Answer: B
Rationale: Matter is defined as anything that has mass and occupies space. Matter can exist as
solids, liquids, gases, and other states.
Question 2
Which of the following is an example of a chemical property?
A. Density
B. Melting point
C. Flammability
D. Boiling point
Answer: C
Rationale: Flammability describes a substance's ability to undergo a chemical reaction with
oxygen. Melting point, boiling point, and density are physical properties.
Question 3
Which change is a physical change?
A. Iron rusting
B. Wood burning
,C. Ice melting
D. Gasoline combusting
Answer: C
Rationale: Melting changes water from solid to liquid without changing its chemical identity.
Rusting, burning wood, and combustion produce new substances.
Question 4
Which particle determines the identity of an element?
A. Neutron
B. Electron
C. Proton
D. Isotope
Answer: C
Rationale: The number of protons in an atom is its atomic number and uniquely identifies the
element.
Question 5
An atom contains 17 protons, 18 neutrons, and 17 electrons. What is its mass number?
A. 17
B. 18
C. 34
D. 35
Answer: D
Rationale: Mass number = protons + neutrons. Therefore, 17 + 18 = 35.
, Question 6
An atom with 11 protons and 10 electrons has what charge?
A. −1
B. 0
C. +1
D. +2
Answer: C
Rationale: The atom has one more positive proton than negative electron: 11 − 10 = +1.
Question 7
Which particle has a negative electrical charge?
A. Proton
B. Neutron
C. Electron
D. Nucleus
Answer: C
Rationale: Electrons carry a negative charge, protons are positive, and neutrons have no net
charge.
Question 8
What does the atomic number of an element represent?
A. Number of neutrons
B. Number of protons
C. Number of protons plus neutrons
D. Number of valence electrons
