American Chemical Society ACS Chemistry Exam
Question 1. Which statement about significant figures is correct?
A. Significant figures are determined only by the unit selected.
B. Every calculator digit should always be reported.
C. The answer should always contain exactly two significant figures.
D. The final result should reflect the precision of the least precise measured quantity used in the calculation.
Correct Answer: D. The final result should reflect the precision of the least precise measured quantity used in
the calculation.
Explanation: The correct statement is that the final result should reflect the precision of the least precise measured
quantity used in the calculation. This is because significant-figure rules prevent a calculated value from implying more
measurement precision than the data support. The distractors either reverse the relevant relationship, misuse a definition,
or ignore a required condition. Recognizing the governing principle first is usually more reliable than choosing an answer
from surface wording.
Question 2. A student is solving a general-chemistry problem involving significant figures. Which
approach is most scientifically sound?
A. The answer should always contain exactly two significant figures.
B. The final result should reflect the precision of the least precise measured quantity used in the calculation.
C. Every calculator digit should always be reported.
D. Significant figures are determined only by the unit selected.
Correct Answer: B. The final result should reflect the precision of the least precise measured quantity used in
the calculation.
Explanation: The sound approach is based on the fact that the final result should reflect the precision of the least precise
measured quantity used in the calculation. The underlying chemistry is that significant-figure rules prevent a calculated
value from implying more measurement precision than the data support. The other choices conflict with the accepted
model or omit information required for a valid conclusion. ACS-style items often reward applying the principle to the stated
conditions rather than relying on a memorized keyword.
Question 3. During review of significant figures, which claim should be corrected?
A. Every calculator digit should always be reported.
B. A conclusion should remain consistent with conservation laws and the governing chemical model.
C. The final result should reflect the precision of the least precise measured quantity used in the calculation.
D. The concept should be applied with attention to the stated conditions and units.
Correct Answer: A. Every calculator digit should always be reported.
Explanation: The claim that should be corrected is: Every calculator digit should always be reported. The correct principle
is that the final result should reflect the precision of the least precise measured quantity used in the calculation. The reason
is that significant-figure rules prevent a calculated value from implying more measurement precision than the data support.
The remaining statements are compatible with sound chemical reasoning and do not introduce the identified
misconception.
Page 1
,Question 4. A sample has a mass of 12.6 g and a volume of 3.0 mL. What is its density?
A. 15.6 g/mL
B. 37.8 g/mL
C. 0.24 g/mL
D. 4.20 g/mL
Correct Answer: D. 4.20 g/mL
Explanation: Density is mass divided by volume, so 12.6 g / 3.0 mL = 4.20 g/mL. The units simplify directly to grams per
milliliter. Multiplying or reversing mass and volume does not represent density. The result should be reported with precision
consistent with the measured data.
Question 5. Which statement about density is correct?
A. Density is volume divided by mass and is extensive.
B. Density changes whenever sample size changes, even at fixed conditions.
C. Density is mass divided by volume and is an intensive property.
D. Density and mass are interchangeable quantities.
Correct Answer: C. Density is mass divided by volume and is an intensive property.
Explanation: The correct statement is that density is mass divided by volume and is an intensive property. This is because
for a homogeneous substance at fixed conditions, doubling both mass and volume leaves the mass-to-volume ratio
unchanged. The distractors either reverse the relevant relationship, misuse a definition, or ignore a required condition.
Recognizing the governing principle first is usually more reliable than choosing an answer from surface wording.
Question 6. A student is solving a general-chemistry problem involving density. Which approach is
most scientifically sound?
A. Density and mass are interchangeable quantities.
B. Density changes whenever sample size changes, even at fixed conditions.
C. Density is volume divided by mass and is extensive.
D. Density is mass divided by volume and is an intensive property.
Correct Answer: D. Density is mass divided by volume and is an intensive property.
Explanation: The sound approach is based on the fact that density is mass divided by volume and is an intensive property.
The underlying chemistry is that for a homogeneous substance at fixed conditions, doubling both mass and volume leaves
the mass-to-volume ratio unchanged. The other choices conflict with the accepted model or omit information required for a
valid conclusion. ACS-style items often reward applying the principle to the stated conditions rather than relying on a
memorized keyword.
Question 7. During review of density, which claim should be corrected?
A. A conclusion should remain consistent with conservation laws and the governing chemical model.
B. Density changes whenever sample size changes, even at fixed conditions.
C. The concept should be applied with attention to the stated conditions and units.
D. Density is mass divided by volume and is an intensive property.
Correct Answer: B. Density changes whenever sample size changes, even at fixed conditions.
Explanation: The claim that should be corrected is: Density changes whenever sample size changes, even at fixed
conditions. The correct principle is that density is mass divided by volume and is an intensive property. The reason is that
for a homogeneous substance at fixed conditions, doubling both mass and volume leaves the mass-to-volume ratio
unchanged. The remaining statements are compatible with sound chemical reasoning and do not introduce the identified
misconception.
Page 2
,Question 8. What is 0 degrees C on the Kelvin scale?
A. 273.15 K
B. 0.00 K
C. -273.15 K
D. 0.00 K
Correct Answer: A. 273.15 K
Explanation: Kelvin temperature equals Celsius temperature plus 273.15, giving 273.15 K. Kelvin and Celsius intervals
are the same size but have different zero points. Subtracting 273.15 converts in the opposite direction.
Absolute-temperature calculations in chemistry should use Kelvin.
Question 9. Which statement about dimensional analysis is correct?
A. Conversion factors must always be multiplied in the same orientation.
B. Units can be ignored if the numerical value seems reasonable.
C. A conversion factor changes the physical quantity being measured.
D. Conversion factors equal to one can be arranged so unwanted units cancel and the desired unit remains.
Correct Answer: D. Conversion factors equal to one can be arranged so unwanted units cancel and the desired
unit remains.
Explanation: The correct statement is that conversion factors equal to one can be arranged so unwanted units cancel and
the desired unit remains. This is because tracking units algebraically is a reliable way to detect setup errors in multistep
conversions. The distractors either reverse the relevant relationship, misuse a definition, or ignore a required condition.
Recognizing the governing principle first is usually more reliable than choosing an answer from surface wording.
Question 10. A student is solving a general-chemistry problem involving dimensional analysis. Which
approach is most scientifically sound?
A. Conversion factors must always be multiplied in the same orientation.
B. Conversion factors equal to one can be arranged so unwanted units cancel and the desired unit remains.
C. A conversion factor changes the physical quantity being measured.
D. Units can be ignored if the numerical value seems reasonable.
Correct Answer: B. Conversion factors equal to one can be arranged so unwanted units cancel and the desired
unit remains.
Explanation: The sound approach is based on the fact that conversion factors equal to one can be arranged so unwanted
units cancel and the desired unit remains. The underlying chemistry is that tracking units algebraically is a reliable way to
detect setup errors in multistep conversions. The other choices conflict with the accepted model or omit information
required for a valid conclusion. ACS-style items often reward applying the principle to the stated conditions rather than
relying on a memorized keyword.
Question 11. During review of dimensional analysis, which claim should be corrected?
A. A conclusion should remain consistent with conservation laws and the governing chemical model.
B. Conversion factors equal to one can be arranged so unwanted units cancel and the desired unit remains.
C. A conversion factor changes the physical quantity being measured.
D. The concept should be applied with attention to the stated conditions and units.
Correct Answer: C. A conversion factor changes the physical quantity being measured.
Explanation: The claim that should be corrected is: A conversion factor changes the physical quantity being measured.
The correct principle is that conversion factors equal to one can be arranged so unwanted units cancel and the desired unit
remains. The reason is that tracking units algebraically is a reliable way to detect setup errors in multistep conversions. The
remaining statements are compatible with sound chemical reasoning and do not introduce the identified misconception.
Page 3
, Question 12. A sample has a mass of 18.4 g and a volume of 4.0 mL. What is its density?
A. 73.6 g/mL
B. 22.4 g/mL
C. 4.60 g/mL
D. 0.22 g/mL
Correct Answer: C. 4.60 g/mL
Explanation: Density is mass divided by volume, so 18.4 g / 4.0 mL = 4.60 g/mL. The units simplify directly to grams per
milliliter. Multiplying or reversing mass and volume does not represent density. The result should be reported with precision
consistent with the measured data.
Question 13. Which statement about temperature scales is correct?
A. Negative Kelvin temperatures are routine in general chemistry calculations.
B. Kelvin temperature is obtained from Celsius temperature by adding approximately 273.15.
C. Zero degrees Celsius is absolute zero.
D. Kelvin and Celsius have different-sized degree intervals.
Correct Answer: B. Kelvin temperature is obtained from Celsius temperature by adding approximately 273.15.
Explanation: The correct statement is that kelvin temperature is obtained from Celsius temperature by adding
approximately 273.15. This is because kelvin and Celsius use the same interval size, but their zero points differ. The
distractors either reverse the relevant relationship, misuse a definition, or ignore a required condition. Recognizing the
governing principle first is usually more reliable than choosing an answer from surface wording.
Question 14. A student is solving a general-chemistry problem involving temperature scales. Which
approach is most scientifically sound?
A. Kelvin and Celsius have different-sized degree intervals.
B. Negative Kelvin temperatures are routine in general chemistry calculations.
C. Kelvin temperature is obtained from Celsius temperature by adding approximately 273.15.
D. Zero degrees Celsius is absolute zero.
Correct Answer: C. Kelvin temperature is obtained from Celsius temperature by adding approximately 273.15.
Explanation: The sound approach is based on the fact that kelvin temperature is obtained from Celsius temperature by
adding approximately 273.15. The underlying chemistry is that kelvin and Celsius use the same interval size, but their zero
points differ. The other choices conflict with the accepted model or omit information required for a valid conclusion.
ACS-style items often reward applying the principle to the stated conditions rather than relying on a memorized keyword.
Question 15. During review of temperature scales, which claim should be corrected?
A. A conclusion should remain consistent with conservation laws and the governing chemical model.
B. Kelvin temperature is obtained from Celsius temperature by adding approximately 273.15.
C. The concept should be applied with attention to the stated conditions and units.
D. Kelvin and Celsius have different-sized degree intervals.
Correct Answer: D. Kelvin and Celsius have different-sized degree intervals.
Explanation: The claim that should be corrected is: Kelvin and Celsius have different-sized degree intervals. The correct
principle is that kelvin temperature is obtained from Celsius temperature by adding approximately 273.15. The reason is
that kelvin and Celsius use the same interval size, but their zero points differ. The remaining statements are compatible
with sound chemical reasoning and do not introduce the identified misconception.
Page 4
Question 1. Which statement about significant figures is correct?
A. Significant figures are determined only by the unit selected.
B. Every calculator digit should always be reported.
C. The answer should always contain exactly two significant figures.
D. The final result should reflect the precision of the least precise measured quantity used in the calculation.
Correct Answer: D. The final result should reflect the precision of the least precise measured quantity used in
the calculation.
Explanation: The correct statement is that the final result should reflect the precision of the least precise measured
quantity used in the calculation. This is because significant-figure rules prevent a calculated value from implying more
measurement precision than the data support. The distractors either reverse the relevant relationship, misuse a definition,
or ignore a required condition. Recognizing the governing principle first is usually more reliable than choosing an answer
from surface wording.
Question 2. A student is solving a general-chemistry problem involving significant figures. Which
approach is most scientifically sound?
A. The answer should always contain exactly two significant figures.
B. The final result should reflect the precision of the least precise measured quantity used in the calculation.
C. Every calculator digit should always be reported.
D. Significant figures are determined only by the unit selected.
Correct Answer: B. The final result should reflect the precision of the least precise measured quantity used in
the calculation.
Explanation: The sound approach is based on the fact that the final result should reflect the precision of the least precise
measured quantity used in the calculation. The underlying chemistry is that significant-figure rules prevent a calculated
value from implying more measurement precision than the data support. The other choices conflict with the accepted
model or omit information required for a valid conclusion. ACS-style items often reward applying the principle to the stated
conditions rather than relying on a memorized keyword.
Question 3. During review of significant figures, which claim should be corrected?
A. Every calculator digit should always be reported.
B. A conclusion should remain consistent with conservation laws and the governing chemical model.
C. The final result should reflect the precision of the least precise measured quantity used in the calculation.
D. The concept should be applied with attention to the stated conditions and units.
Correct Answer: A. Every calculator digit should always be reported.
Explanation: The claim that should be corrected is: Every calculator digit should always be reported. The correct principle
is that the final result should reflect the precision of the least precise measured quantity used in the calculation. The reason
is that significant-figure rules prevent a calculated value from implying more measurement precision than the data support.
The remaining statements are compatible with sound chemical reasoning and do not introduce the identified
misconception.
Page 1
,Question 4. A sample has a mass of 12.6 g and a volume of 3.0 mL. What is its density?
A. 15.6 g/mL
B. 37.8 g/mL
C. 0.24 g/mL
D. 4.20 g/mL
Correct Answer: D. 4.20 g/mL
Explanation: Density is mass divided by volume, so 12.6 g / 3.0 mL = 4.20 g/mL. The units simplify directly to grams per
milliliter. Multiplying or reversing mass and volume does not represent density. The result should be reported with precision
consistent with the measured data.
Question 5. Which statement about density is correct?
A. Density is volume divided by mass and is extensive.
B. Density changes whenever sample size changes, even at fixed conditions.
C. Density is mass divided by volume and is an intensive property.
D. Density and mass are interchangeable quantities.
Correct Answer: C. Density is mass divided by volume and is an intensive property.
Explanation: The correct statement is that density is mass divided by volume and is an intensive property. This is because
for a homogeneous substance at fixed conditions, doubling both mass and volume leaves the mass-to-volume ratio
unchanged. The distractors either reverse the relevant relationship, misuse a definition, or ignore a required condition.
Recognizing the governing principle first is usually more reliable than choosing an answer from surface wording.
Question 6. A student is solving a general-chemistry problem involving density. Which approach is
most scientifically sound?
A. Density and mass are interchangeable quantities.
B. Density changes whenever sample size changes, even at fixed conditions.
C. Density is volume divided by mass and is extensive.
D. Density is mass divided by volume and is an intensive property.
Correct Answer: D. Density is mass divided by volume and is an intensive property.
Explanation: The sound approach is based on the fact that density is mass divided by volume and is an intensive property.
The underlying chemistry is that for a homogeneous substance at fixed conditions, doubling both mass and volume leaves
the mass-to-volume ratio unchanged. The other choices conflict with the accepted model or omit information required for a
valid conclusion. ACS-style items often reward applying the principle to the stated conditions rather than relying on a
memorized keyword.
Question 7. During review of density, which claim should be corrected?
A. A conclusion should remain consistent with conservation laws and the governing chemical model.
B. Density changes whenever sample size changes, even at fixed conditions.
C. The concept should be applied with attention to the stated conditions and units.
D. Density is mass divided by volume and is an intensive property.
Correct Answer: B. Density changes whenever sample size changes, even at fixed conditions.
Explanation: The claim that should be corrected is: Density changes whenever sample size changes, even at fixed
conditions. The correct principle is that density is mass divided by volume and is an intensive property. The reason is that
for a homogeneous substance at fixed conditions, doubling both mass and volume leaves the mass-to-volume ratio
unchanged. The remaining statements are compatible with sound chemical reasoning and do not introduce the identified
misconception.
Page 2
,Question 8. What is 0 degrees C on the Kelvin scale?
A. 273.15 K
B. 0.00 K
C. -273.15 K
D. 0.00 K
Correct Answer: A. 273.15 K
Explanation: Kelvin temperature equals Celsius temperature plus 273.15, giving 273.15 K. Kelvin and Celsius intervals
are the same size but have different zero points. Subtracting 273.15 converts in the opposite direction.
Absolute-temperature calculations in chemistry should use Kelvin.
Question 9. Which statement about dimensional analysis is correct?
A. Conversion factors must always be multiplied in the same orientation.
B. Units can be ignored if the numerical value seems reasonable.
C. A conversion factor changes the physical quantity being measured.
D. Conversion factors equal to one can be arranged so unwanted units cancel and the desired unit remains.
Correct Answer: D. Conversion factors equal to one can be arranged so unwanted units cancel and the desired
unit remains.
Explanation: The correct statement is that conversion factors equal to one can be arranged so unwanted units cancel and
the desired unit remains. This is because tracking units algebraically is a reliable way to detect setup errors in multistep
conversions. The distractors either reverse the relevant relationship, misuse a definition, or ignore a required condition.
Recognizing the governing principle first is usually more reliable than choosing an answer from surface wording.
Question 10. A student is solving a general-chemistry problem involving dimensional analysis. Which
approach is most scientifically sound?
A. Conversion factors must always be multiplied in the same orientation.
B. Conversion factors equal to one can be arranged so unwanted units cancel and the desired unit remains.
C. A conversion factor changes the physical quantity being measured.
D. Units can be ignored if the numerical value seems reasonable.
Correct Answer: B. Conversion factors equal to one can be arranged so unwanted units cancel and the desired
unit remains.
Explanation: The sound approach is based on the fact that conversion factors equal to one can be arranged so unwanted
units cancel and the desired unit remains. The underlying chemistry is that tracking units algebraically is a reliable way to
detect setup errors in multistep conversions. The other choices conflict with the accepted model or omit information
required for a valid conclusion. ACS-style items often reward applying the principle to the stated conditions rather than
relying on a memorized keyword.
Question 11. During review of dimensional analysis, which claim should be corrected?
A. A conclusion should remain consistent with conservation laws and the governing chemical model.
B. Conversion factors equal to one can be arranged so unwanted units cancel and the desired unit remains.
C. A conversion factor changes the physical quantity being measured.
D. The concept should be applied with attention to the stated conditions and units.
Correct Answer: C. A conversion factor changes the physical quantity being measured.
Explanation: The claim that should be corrected is: A conversion factor changes the physical quantity being measured.
The correct principle is that conversion factors equal to one can be arranged so unwanted units cancel and the desired unit
remains. The reason is that tracking units algebraically is a reliable way to detect setup errors in multistep conversions. The
remaining statements are compatible with sound chemical reasoning and do not introduce the identified misconception.
Page 3
, Question 12. A sample has a mass of 18.4 g and a volume of 4.0 mL. What is its density?
A. 73.6 g/mL
B. 22.4 g/mL
C. 4.60 g/mL
D. 0.22 g/mL
Correct Answer: C. 4.60 g/mL
Explanation: Density is mass divided by volume, so 18.4 g / 4.0 mL = 4.60 g/mL. The units simplify directly to grams per
milliliter. Multiplying or reversing mass and volume does not represent density. The result should be reported with precision
consistent with the measured data.
Question 13. Which statement about temperature scales is correct?
A. Negative Kelvin temperatures are routine in general chemistry calculations.
B. Kelvin temperature is obtained from Celsius temperature by adding approximately 273.15.
C. Zero degrees Celsius is absolute zero.
D. Kelvin and Celsius have different-sized degree intervals.
Correct Answer: B. Kelvin temperature is obtained from Celsius temperature by adding approximately 273.15.
Explanation: The correct statement is that kelvin temperature is obtained from Celsius temperature by adding
approximately 273.15. This is because kelvin and Celsius use the same interval size, but their zero points differ. The
distractors either reverse the relevant relationship, misuse a definition, or ignore a required condition. Recognizing the
governing principle first is usually more reliable than choosing an answer from surface wording.
Question 14. A student is solving a general-chemistry problem involving temperature scales. Which
approach is most scientifically sound?
A. Kelvin and Celsius have different-sized degree intervals.
B. Negative Kelvin temperatures are routine in general chemistry calculations.
C. Kelvin temperature is obtained from Celsius temperature by adding approximately 273.15.
D. Zero degrees Celsius is absolute zero.
Correct Answer: C. Kelvin temperature is obtained from Celsius temperature by adding approximately 273.15.
Explanation: The sound approach is based on the fact that kelvin temperature is obtained from Celsius temperature by
adding approximately 273.15. The underlying chemistry is that kelvin and Celsius use the same interval size, but their zero
points differ. The other choices conflict with the accepted model or omit information required for a valid conclusion.
ACS-style items often reward applying the principle to the stated conditions rather than relying on a memorized keyword.
Question 15. During review of temperature scales, which claim should be corrected?
A. A conclusion should remain consistent with conservation laws and the governing chemical model.
B. Kelvin temperature is obtained from Celsius temperature by adding approximately 273.15.
C. The concept should be applied with attention to the stated conditions and units.
D. Kelvin and Celsius have different-sized degree intervals.
Correct Answer: D. Kelvin and Celsius have different-sized degree intervals.
Explanation: The claim that should be corrected is: Kelvin and Celsius have different-sized degree intervals. The correct
principle is that kelvin temperature is obtained from Celsius temperature by adding approximately 273.15. The reason is
that kelvin and Celsius use the same interval size, but their zero points differ. The remaining statements are compatible
with sound chemical reasoning and do not introduce the identified misconception.
Page 4
