COMPREHENSIVE EXAMINATION: INTRODUCTORY CHEMISTRY SOLUTIONS
BASED ON TRO'S 7TH EDITION –
SECTION A: MATTER, MEASUREMENT, AND PROBLEM SOLVING
1. Which of the following represents a chemical property of matter?
A. Density of water is 1.00 g/mL at 4°C
B. Iron has a melting point of 1538°C
C. Sodium reacts vigorously with water
D. Copper conducts electricity efficiently
Answer: C (Reactivity with water describes how sodium chemically transforms into new
substances, which is a chemical property. Options A, B, and D describe physical properties
that can be observed without changing the substance's chemical identity.)
2. A graduated cylinder contains 25.0 mL of water. When a metal object with a mass of
68.5 g is submerged, the water level rises to 33.2 mL. What is the density of the metal?
A. 8.35 g/mL
B. 2.75 g/mL
C. 6.82 g/mL
D. 9.15 g/mL
Answer: A (Volume displaced = 33.2 mL - 25.0 mL = 8.2 mL. Density = mass/volume = 68.5
g / 8.2 mL = 8.35 g/mL. The object's volume equals the volume of water displaced by
Archimedes' principle.)
,3. Which measurement contains three significant figures?
A. 0.00450 m
B. 4500 m
C. 4.50 × 10³ m
D. 0.045 m
Answer: C (4.50 × 10³ contains three significant figures (4, 5, and 0). Scientific notation
clearly indicates significant figures. Option A has three but the leading zeros before 4 are
not significant; only 4,5,0 are significant. Option B is ambiguous without decimal point.
Option D has two significant figures.)
4. Convert 75.0°F to Kelvin.
A. 297 K
B. 303 K
C. 287 K
D. 310 K
Answer: A (°C = (°F - 32) × 5/9 = (75.0 - 32) × 5/9 = 23.9°C. K = °C + 273.15 = 23.9 + 273.15 =
297.05 K ≈ 297 K. Remember that Kelvin uses absolute zero as its starting point.)
5. Which of the following is an intensive property?
A. Mass
B. Volume
C. Temperature
D. Number of moles
Answer: C (Temperature is intensive because it does not depend on the amount of
substance present. Mass, volume, and number of moles are extensive properties that scale
with the quantity of matter.)
6. A student measures the mass of a sample three times: 5.23 g, 5.25 g, and 5.24 g. The
true mass is 5.00 g. The measurements are:
A. Accurate and precise
B. Accurate but not precise
C. Precise but not accurate
D. Neither accurate nor precise
,Answer: C (The measurements are close to each other (precise) but far from the true value
of 5.00 g (not accurate). Precision refers to reproducibility while accuracy refers to
closeness to the true value.)
7. How many milliliters are in 2.50 L?
A. 250 mL
B. 2500 mL
C. 0.250 mL
D. 25.0 mL
Answer: B (1 L = 1000 mL, so 2.50 L × 1000 mL/L = 2500 mL. The conversion factor relates
liters to milliliters with the prefix milli- meaning 1/1000.)
8. The density of ethanol is 0.789 g/mL. What is the mass of 150.0 mL of ethanol?
A. 190 g
B. 118 g
C. 150 g
D. 95.0 g
Answer: B (Mass = density × volume = 0.789 g/mL × 150.0 mL = 118.35 g ≈ 118 g. The
density is a conversion factor between mass and volume for this specific substance.)
9. Which of the following is NOT a SI base unit?
A. Meter
B. Kilogram
C. Liter
D. Second
Answer: C (Liter is not an SI base unit; it is a derived unit for volume. The SI base units
include meter (length), kilogram (mass), second (time), ampere (electric current), kelvin
(temperature), mole (amount of substance), and candela (luminous intensity).)
10. Calculate: (4.56 × 10²) × (2.3 × 10⁻³)
A. 1.05 × 10⁰
B. 1.05 × 10¹
, C. 1.05 × 10⁻¹
D. 1.05 × 10⁻²
Answer: A (Multiply coefficients: 4.56 × 2.3 = 10.488. Add exponents: 2 + (-3) = -1. Result =
10.488 × 10⁻¹ = 1.0488 × 10⁰ ≈ 1.05 × 10⁰. The answer should have two significant figures
because 2.3 has two.)
11. Which statement about the scientific method is FALSE?
A. Hypotheses are testable explanations
B. Laws summarize observed behavior
C. Theories are absolute truth and never change
D. Experiments must be reproducible
Answer: C (Theories are well-substantiated explanations that can be modified or replaced
as new evidence emerges. They are not absolute truth; science is self-correcting and
theories evolve with new discoveries.)
12. A sample has a mass of 25.0 g and a volume of 10.0 cm³. What is its density in
kg/m³?
A. 2500 kg/m³
B. 2.50 kg/m³
C. 250 kg/m³
D. 25,000 kg/m³
Answer: A (Density = 25.0 g/10.0 cm³ = 2.50 g/cm³. Convert: 2.50 g/cm³ × (1 kg/1000 g) ×
(100 cm/1 m)³ = 2.50 × 1000 kg/m³ = 2500 kg/m³. Remember that 1 g/cm³ = 1000 kg/m³.)
13. The prefix that means 10⁻⁶ is:
A. Mega
B. Micro
C. Nano
D. Milli
Answer: B (Micro (μ) means 10⁻⁶ or one-millionth. Mega means 10⁶, nano means 10⁻⁹, and
milli means 10⁻³. These prefixes are part of the metric system used in scientific
measurements.)
BASED ON TRO'S 7TH EDITION –
SECTION A: MATTER, MEASUREMENT, AND PROBLEM SOLVING
1. Which of the following represents a chemical property of matter?
A. Density of water is 1.00 g/mL at 4°C
B. Iron has a melting point of 1538°C
C. Sodium reacts vigorously with water
D. Copper conducts electricity efficiently
Answer: C (Reactivity with water describes how sodium chemically transforms into new
substances, which is a chemical property. Options A, B, and D describe physical properties
that can be observed without changing the substance's chemical identity.)
2. A graduated cylinder contains 25.0 mL of water. When a metal object with a mass of
68.5 g is submerged, the water level rises to 33.2 mL. What is the density of the metal?
A. 8.35 g/mL
B. 2.75 g/mL
C. 6.82 g/mL
D. 9.15 g/mL
Answer: A (Volume displaced = 33.2 mL - 25.0 mL = 8.2 mL. Density = mass/volume = 68.5
g / 8.2 mL = 8.35 g/mL. The object's volume equals the volume of water displaced by
Archimedes' principle.)
,3. Which measurement contains three significant figures?
A. 0.00450 m
B. 4500 m
C. 4.50 × 10³ m
D. 0.045 m
Answer: C (4.50 × 10³ contains three significant figures (4, 5, and 0). Scientific notation
clearly indicates significant figures. Option A has three but the leading zeros before 4 are
not significant; only 4,5,0 are significant. Option B is ambiguous without decimal point.
Option D has two significant figures.)
4. Convert 75.0°F to Kelvin.
A. 297 K
B. 303 K
C. 287 K
D. 310 K
Answer: A (°C = (°F - 32) × 5/9 = (75.0 - 32) × 5/9 = 23.9°C. K = °C + 273.15 = 23.9 + 273.15 =
297.05 K ≈ 297 K. Remember that Kelvin uses absolute zero as its starting point.)
5. Which of the following is an intensive property?
A. Mass
B. Volume
C. Temperature
D. Number of moles
Answer: C (Temperature is intensive because it does not depend on the amount of
substance present. Mass, volume, and number of moles are extensive properties that scale
with the quantity of matter.)
6. A student measures the mass of a sample three times: 5.23 g, 5.25 g, and 5.24 g. The
true mass is 5.00 g. The measurements are:
A. Accurate and precise
B. Accurate but not precise
C. Precise but not accurate
D. Neither accurate nor precise
,Answer: C (The measurements are close to each other (precise) but far from the true value
of 5.00 g (not accurate). Precision refers to reproducibility while accuracy refers to
closeness to the true value.)
7. How many milliliters are in 2.50 L?
A. 250 mL
B. 2500 mL
C. 0.250 mL
D. 25.0 mL
Answer: B (1 L = 1000 mL, so 2.50 L × 1000 mL/L = 2500 mL. The conversion factor relates
liters to milliliters with the prefix milli- meaning 1/1000.)
8. The density of ethanol is 0.789 g/mL. What is the mass of 150.0 mL of ethanol?
A. 190 g
B. 118 g
C. 150 g
D. 95.0 g
Answer: B (Mass = density × volume = 0.789 g/mL × 150.0 mL = 118.35 g ≈ 118 g. The
density is a conversion factor between mass and volume for this specific substance.)
9. Which of the following is NOT a SI base unit?
A. Meter
B. Kilogram
C. Liter
D. Second
Answer: C (Liter is not an SI base unit; it is a derived unit for volume. The SI base units
include meter (length), kilogram (mass), second (time), ampere (electric current), kelvin
(temperature), mole (amount of substance), and candela (luminous intensity).)
10. Calculate: (4.56 × 10²) × (2.3 × 10⁻³)
A. 1.05 × 10⁰
B. 1.05 × 10¹
, C. 1.05 × 10⁻¹
D. 1.05 × 10⁻²
Answer: A (Multiply coefficients: 4.56 × 2.3 = 10.488. Add exponents: 2 + (-3) = -1. Result =
10.488 × 10⁻¹ = 1.0488 × 10⁰ ≈ 1.05 × 10⁰. The answer should have two significant figures
because 2.3 has two.)
11. Which statement about the scientific method is FALSE?
A. Hypotheses are testable explanations
B. Laws summarize observed behavior
C. Theories are absolute truth and never change
D. Experiments must be reproducible
Answer: C (Theories are well-substantiated explanations that can be modified or replaced
as new evidence emerges. They are not absolute truth; science is self-correcting and
theories evolve with new discoveries.)
12. A sample has a mass of 25.0 g and a volume of 10.0 cm³. What is its density in
kg/m³?
A. 2500 kg/m³
B. 2.50 kg/m³
C. 250 kg/m³
D. 25,000 kg/m³
Answer: A (Density = 25.0 g/10.0 cm³ = 2.50 g/cm³. Convert: 2.50 g/cm³ × (1 kg/1000 g) ×
(100 cm/1 m)³ = 2.50 × 1000 kg/m³ = 2500 kg/m³. Remember that 1 g/cm³ = 1000 kg/m³.)
13. The prefix that means 10⁻⁶ is:
A. Mega
B. Micro
C. Nano
D. Milli
Answer: B (Micro (μ) means 10⁻⁶ or one-millionth. Mega means 10⁶, nano means 10⁻⁹, and
milli means 10⁻³. These prefixes are part of the metric system used in scientific
measurements.)
