OBJECTIVE ASSESSMENT
200+ QUESTIONS & ANSWERS WITH
RATIONALES
,WGU D425 Introduction to Chemistry Objective Assessment (OA) Practice Exam 2026/2027
Section 7: Chemical Bonding and Molecular Structure (Continued)
Question 1
Chemistry is the study of:
• A) Life and living organisms
• B) Matter and its transformations
• C) Energy and motion
• D) Earth and its composition
Answer: B
Rationale: Chemistry is the study of matter—its composition, properties, and transformations.
It examines how substances interact, combine, and change to form new substances. Biology
studies life, physics studies energy and motion, and geology studies Earth .
Question 2
Which type of property does NOT depend on the amount of substance present?
• A) Extensive property
• B) Intensive property
• C) Physical property
• D) Chemical property
Answer: B
,Rationale: Intensive properties do not depend on the amount of matter present and include
characteristics such as density, color, and melting point. Extensive properties, in contrast,
depend on the amount of matter (e.g., mass and volume) .
Question 3
A student measures the mass of a metal cube as 54.3 g. If the cube has a volume of 6.0 cm³,
what is its density?
• A) 0.11 g/cm³
• B) 9.05 g/cm³
• C) 9.1 g/cm³
• D) 54.3 g/cm³
Answer: C
Rationale: Density is calculated by dividing mass by volume (D = m/v). The calculation is 54.3 g
÷ 6.0 cm³ = 9.05 g/cm³. However, because the volume (6.0) has two significant figures, the
answer must be rounded to 9.1 g/cm³ .
Question 4
Which of the following represents a chemical change?
• A) Melting of ice
• B) Dissolving sugar in water
• C) Tearing a piece of paper
• D) Souring of milk
Answer: D
, Rationale: A chemical change results in the formation of a new substance. The souring of milk
occurs when bacteria convert lactose into lactic acid, changing the chemical composition.
Melting, dissolving, and tearing are physical changes .
Question 5
What is the smallest unit of an element that retains the chemical properties of that element?
• A) Molecule
• B) Atom
• C) Electron
• D) Proton
Answer: B
Rationale: An atom is the fundamental building block of matter and the smallest unit of an
element that retains the chemical properties of that element. Electrons and protons are
subatomic particles that do not, by themselves, retain the properties of an element .
Question 6
Which subatomic particle has a negative charge and orbits the nucleus?
• A) Proton
• B) Neutron
• C) Electron
• D) Positron
Answer: C
200+ QUESTIONS & ANSWERS WITH
RATIONALES
,WGU D425 Introduction to Chemistry Objective Assessment (OA) Practice Exam 2026/2027
Section 7: Chemical Bonding and Molecular Structure (Continued)
Question 1
Chemistry is the study of:
• A) Life and living organisms
• B) Matter and its transformations
• C) Energy and motion
• D) Earth and its composition
Answer: B
Rationale: Chemistry is the study of matter—its composition, properties, and transformations.
It examines how substances interact, combine, and change to form new substances. Biology
studies life, physics studies energy and motion, and geology studies Earth .
Question 2
Which type of property does NOT depend on the amount of substance present?
• A) Extensive property
• B) Intensive property
• C) Physical property
• D) Chemical property
Answer: B
,Rationale: Intensive properties do not depend on the amount of matter present and include
characteristics such as density, color, and melting point. Extensive properties, in contrast,
depend on the amount of matter (e.g., mass and volume) .
Question 3
A student measures the mass of a metal cube as 54.3 g. If the cube has a volume of 6.0 cm³,
what is its density?
• A) 0.11 g/cm³
• B) 9.05 g/cm³
• C) 9.1 g/cm³
• D) 54.3 g/cm³
Answer: C
Rationale: Density is calculated by dividing mass by volume (D = m/v). The calculation is 54.3 g
÷ 6.0 cm³ = 9.05 g/cm³. However, because the volume (6.0) has two significant figures, the
answer must be rounded to 9.1 g/cm³ .
Question 4
Which of the following represents a chemical change?
• A) Melting of ice
• B) Dissolving sugar in water
• C) Tearing a piece of paper
• D) Souring of milk
Answer: D
, Rationale: A chemical change results in the formation of a new substance. The souring of milk
occurs when bacteria convert lactose into lactic acid, changing the chemical composition.
Melting, dissolving, and tearing are physical changes .
Question 5
What is the smallest unit of an element that retains the chemical properties of that element?
• A) Molecule
• B) Atom
• C) Electron
• D) Proton
Answer: B
Rationale: An atom is the fundamental building block of matter and the smallest unit of an
element that retains the chemical properties of that element. Electrons and protons are
subatomic particles that do not, by themselves, retain the properties of an element .
Question 6
Which subatomic particle has a negative charge and orbits the nucleus?
• A) Proton
• B) Neutron
• C) Electron
• D) Positron
Answer: C
