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CHEMISTRY: THE MOLECULAR NATURE OF MATTER, 8TH EDITION
(JESPERSEN) — COMPLETE STUDY - EXAM QUESTIONS LATEST EDITION
2026 – 2027 VERSION SOLVED QUESTIONS & ANSWERS
Chemistry: The Molecular Nature of Matter, 8th Edition (Jespersen) — Questions
with Rationales
1. Which of the following is the logical progression of elements formed in a star?
A) Hydrogen → helium → carbon → oxygen → iron
B) Iron → oxygen → carbon → helium → hydrogen
C) Helium → hydrogen → iron → carbon → oxygen
D) Carbon → hydrogen → helium → oxygen → iron
Correct Answer: A
Rationale: Stellar nucleosynthesis begins with hydrogen fusion to helium, followed by
helium fusion to carbon, oxygen, and heavier elements up to iron. Iron is the heaviest
element formed in a star prior to a supernova.
2. Why is iron the heaviest element formed in a star prior to the formation of a
supernova?
A) Iron has the highest binding energy per nucleon
B) Iron is the most abundant element in the universe
C) Iron has the lowest atomic number
D) Iron is the most reactive element
Correct Answer: A
Rationale: Iron has the highest binding energy per nucleon, meaning fusion beyond iron
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would absorb energy rather than release it. Therefore, fusion stops at iron in stellar
cores.
3. Which of the following is a scientific hypothesis?
A) A well-tested explanation supported by extensive evidence
B) A tentative explanation that can be tested by experiment
C) A statement of fact that cannot be challenged
D) A mathematical equation that describes a natural phenomenon
Correct Answer: B
Rationale: A hypothesis is a tentative, testable explanation for an observation. It must
be falsifiable and subject to experimentation.
4. How many significant figures are in the measurement 0.0045070 g?
A) 3
B) 4
C) 5
D) 7
Correct Answer: C
Rationale: Leading zeros are not significant. The digits 4, 5, 0, 7, and the trailing 0 after
the decimal are significant, giving 5 significant figures.
5. Express 0.000678 in scientific notation.
A) 6.78 × 10⁻⁴
B) 6.78 × 10⁴
C) 67.8 × 10⁻⁵
D) 0.678 × 10⁻³
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Correct Answer: A
Rationale: Move the decimal point four places to the right to obtain 6.78. Since the
original number is less than 1, the exponent is negative: 6.78 × 10⁻⁴.
6. Which of the following is an example of a chemical change?
A) Melting ice
B) Dissolving sugar in water
C) Burning methane
D) Evaporating alcohol
Correct Answer: C
Rationale: Burning methane produces new substances (CO₂ and H₂O), indicating a
chemical change. The other options are physical changes.
7. What is the correct SI unit for mass?
A) Pound
B) Gram
C) Kilogram
D) Ounce
Correct Answer: C
Rationale: The SI base unit for mass is the kilogram (kg). The gram is a derived unit.
8. Convert 25.0 °C to Kelvin.
A) 248.15 K
B) 298.15 K
C) 273.15 K
D) 25.0 K
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Correct Answer: B
Rationale: K = °C + 273.15. 25.0 + 273.15 = 298.15 K.
9. Which of the following is a homogeneous mixture?
A) Concrete
B) Saltwater
C) Granite
D) Sand and iron filings
Correct Answer: B
Rationale: Saltwater is a homogeneous mixture because its composition is uniform
throughout.
10. Which of the following represents a physical property?
A) Flammability
B) Reactivity with acid
C) Density
D) Toxicity
Correct Answer: C
Rationale: Density is a physical property that can be measured without changing the
substance's chemical identity.
11. What is the density of a substance with a mass of 45.0 g and a volume of 15.0
mL?
A) 0.333 g/mL
B) 3.00 g/mL
C) 30.0 g/mL
D) 675 g/mL
CHEMISTRY: THE MOLECULAR NATURE OF MATTER, 8TH EDITION
(JESPERSEN) — COMPLETE STUDY - EXAM QUESTIONS LATEST EDITION
2026 – 2027 VERSION SOLVED QUESTIONS & ANSWERS
Chemistry: The Molecular Nature of Matter, 8th Edition (Jespersen) — Questions
with Rationales
1. Which of the following is the logical progression of elements formed in a star?
A) Hydrogen → helium → carbon → oxygen → iron
B) Iron → oxygen → carbon → helium → hydrogen
C) Helium → hydrogen → iron → carbon → oxygen
D) Carbon → hydrogen → helium → oxygen → iron
Correct Answer: A
Rationale: Stellar nucleosynthesis begins with hydrogen fusion to helium, followed by
helium fusion to carbon, oxygen, and heavier elements up to iron. Iron is the heaviest
element formed in a star prior to a supernova.
2. Why is iron the heaviest element formed in a star prior to the formation of a
supernova?
A) Iron has the highest binding energy per nucleon
B) Iron is the most abundant element in the universe
C) Iron has the lowest atomic number
D) Iron is the most reactive element
Correct Answer: A
Rationale: Iron has the highest binding energy per nucleon, meaning fusion beyond iron
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would absorb energy rather than release it. Therefore, fusion stops at iron in stellar
cores.
3. Which of the following is a scientific hypothesis?
A) A well-tested explanation supported by extensive evidence
B) A tentative explanation that can be tested by experiment
C) A statement of fact that cannot be challenged
D) A mathematical equation that describes a natural phenomenon
Correct Answer: B
Rationale: A hypothesis is a tentative, testable explanation for an observation. It must
be falsifiable and subject to experimentation.
4. How many significant figures are in the measurement 0.0045070 g?
A) 3
B) 4
C) 5
D) 7
Correct Answer: C
Rationale: Leading zeros are not significant. The digits 4, 5, 0, 7, and the trailing 0 after
the decimal are significant, giving 5 significant figures.
5. Express 0.000678 in scientific notation.
A) 6.78 × 10⁻⁴
B) 6.78 × 10⁴
C) 67.8 × 10⁻⁵
D) 0.678 × 10⁻³
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Correct Answer: A
Rationale: Move the decimal point four places to the right to obtain 6.78. Since the
original number is less than 1, the exponent is negative: 6.78 × 10⁻⁴.
6. Which of the following is an example of a chemical change?
A) Melting ice
B) Dissolving sugar in water
C) Burning methane
D) Evaporating alcohol
Correct Answer: C
Rationale: Burning methane produces new substances (CO₂ and H₂O), indicating a
chemical change. The other options are physical changes.
7. What is the correct SI unit for mass?
A) Pound
B) Gram
C) Kilogram
D) Ounce
Correct Answer: C
Rationale: The SI base unit for mass is the kilogram (kg). The gram is a derived unit.
8. Convert 25.0 °C to Kelvin.
A) 248.15 K
B) 298.15 K
C) 273.15 K
D) 25.0 K
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Correct Answer: B
Rationale: K = °C + 273.15. 25.0 + 273.15 = 298.15 K.
9. Which of the following is a homogeneous mixture?
A) Concrete
B) Saltwater
C) Granite
D) Sand and iron filings
Correct Answer: B
Rationale: Saltwater is a homogeneous mixture because its composition is uniform
throughout.
10. Which of the following represents a physical property?
A) Flammability
B) Reactivity with acid
C) Density
D) Toxicity
Correct Answer: C
Rationale: Density is a physical property that can be measured without changing the
substance's chemical identity.
11. What is the density of a substance with a mass of 45.0 g and a volume of 15.0
mL?
A) 0.333 g/mL
B) 3.00 g/mL
C) 30.0 g/mL
D) 675 g/mL
