WGU D425 Intro to Chemistry Objective Assessment Actual Exam
2025/2026 | Questions with Verified Answers | 100% Correct | Pass
Guaranteed
SECTION 1: Matter, Measurement & Scientific Method
(Questions 1-25)
Question 1
Which of the following best defines chemistry?
A) The study of living organisms and their interactions
B) The study of matter, its properties, and its transformations
C) The study of energy and its motion
D) The study of Earth's composition and structure
Correct Answer: B
Rationale: Chemistry is specifically the study of matter—its composition, properties,
and the changes it undergoes .
Question 2
A student measures a metal cube with a mass of 54.3 g and a volume of 6.0 cm³. What is
the density of the cube?
A) 0.11 g/cm³
B) 9.1 g/cm³
C) 9.05 g/cm³
D) 54.3 g/cm³
,Correct Answer: B
Rationale: Density = mass/volume = 54.3 g ÷ 6.0 cm³ = 9.05 g/cm³. Since 6.0 has two
significant figures, the answer rounds to 9.1 g/cm³ .
Question 3
Which property does NOT depend on the amount of substance present?
A) Mass
B) Volume
C) Density
D) Length
Correct Answer: C
Rationale: Density is an intensive property. Intensive properties (density, color, melting
point) are independent of sample size. Extensive properties (mass, volume) depend on
amount .
Question 4
Which of the following represents a chemical change?
A) Melting ice
B) Dissolving sugar in water
C) Souring of milk
D) Tearing paper
,Correct Answer: C
Rationale: Souring of milk produces lactic acid (a new substance), making it a chemical
change. Melting, dissolving, and tearing are physical changes .
Question 5
A student records a beaker mass of 120.45 g and adds 2.5 g of solid. What is the total
mass reported with correct significant figures?
A) 122.95 g
B) 123.0 g
C) 123 g
D) 122.9 g
Correct Answer: D
Rationale: When adding measurements, round to the fewest decimal places. 120.45 has
two decimals; 2.5 has one. Result = 122.95 g → rounded to 122.9 g .
Question 6
A sample contains visible quartz veins in granite. How is this classified?
A) Homogeneous mixture
B) Heterogeneous mixture
C) Pure substance
D) Compound
, Correct Answer: B
Rationale: A heterogeneous mixture has physically distinct parts not uniformly
distributed. Visible veins indicate heterogeneity .
Question 7
Convert 45 micrograms per liter to milligrams per liter.
A) 4.5 mg/L
B) 0.045 mg/L
C) 0.45 mg/L
D) 450 mg/L
Correct Answer: B
Rationale: Micro to milli requires dividing by 1,000. 45 ÷ 1,000 = 0.045 mg/L .
Question 8
What is the smallest unit of an element that retains its chemical properties?
A) Molecule
B) Atom
C) Electron
D) Proton
Correct Answer: B
2025/2026 | Questions with Verified Answers | 100% Correct | Pass
Guaranteed
SECTION 1: Matter, Measurement & Scientific Method
(Questions 1-25)
Question 1
Which of the following best defines chemistry?
A) The study of living organisms and their interactions
B) The study of matter, its properties, and its transformations
C) The study of energy and its motion
D) The study of Earth's composition and structure
Correct Answer: B
Rationale: Chemistry is specifically the study of matter—its composition, properties,
and the changes it undergoes .
Question 2
A student measures a metal cube with a mass of 54.3 g and a volume of 6.0 cm³. What is
the density of the cube?
A) 0.11 g/cm³
B) 9.1 g/cm³
C) 9.05 g/cm³
D) 54.3 g/cm³
,Correct Answer: B
Rationale: Density = mass/volume = 54.3 g ÷ 6.0 cm³ = 9.05 g/cm³. Since 6.0 has two
significant figures, the answer rounds to 9.1 g/cm³ .
Question 3
Which property does NOT depend on the amount of substance present?
A) Mass
B) Volume
C) Density
D) Length
Correct Answer: C
Rationale: Density is an intensive property. Intensive properties (density, color, melting
point) are independent of sample size. Extensive properties (mass, volume) depend on
amount .
Question 4
Which of the following represents a chemical change?
A) Melting ice
B) Dissolving sugar in water
C) Souring of milk
D) Tearing paper
,Correct Answer: C
Rationale: Souring of milk produces lactic acid (a new substance), making it a chemical
change. Melting, dissolving, and tearing are physical changes .
Question 5
A student records a beaker mass of 120.45 g and adds 2.5 g of solid. What is the total
mass reported with correct significant figures?
A) 122.95 g
B) 123.0 g
C) 123 g
D) 122.9 g
Correct Answer: D
Rationale: When adding measurements, round to the fewest decimal places. 120.45 has
two decimals; 2.5 has one. Result = 122.95 g → rounded to 122.9 g .
Question 6
A sample contains visible quartz veins in granite. How is this classified?
A) Homogeneous mixture
B) Heterogeneous mixture
C) Pure substance
D) Compound
, Correct Answer: B
Rationale: A heterogeneous mixture has physically distinct parts not uniformly
distributed. Visible veins indicate heterogeneity .
Question 7
Convert 45 micrograms per liter to milligrams per liter.
A) 4.5 mg/L
B) 0.045 mg/L
C) 0.45 mg/L
D) 450 mg/L
Correct Answer: B
Rationale: Micro to milli requires dividing by 1,000. 45 ÷ 1,000 = 0.045 mg/L .
Question 8
What is the smallest unit of an element that retains its chemical properties?
A) Molecule
B) Atom
C) Electron
D) Proton
Correct Answer: B
