,Verified CHEM 103 Final Module Exam-
General Chemistry I-Portage - (26/27) Actual
(PDF)
1. Convert 0.000450 to exponential (scientific notation) form.
A) 4.50 × 10⁻⁴
B) 4.50 × 10⁴
C) 45.0 × 10⁻⁵
D) 0.450 × 10⁻³
Correct Answer: A) 4.50 × 10⁻⁴
Rationale: Move the decimal point 4 places to the right to place it after the first non-zero digit (4.50).
Since the original number is smaller than 1, the exponent is negative. Option B has the wrong
exponent sign, C has two digits before the decimal, and D has zero before the decimal.
2. How many significant figures are in the measurement 0.005030?
A) 4
B) 5
C) 6
D) 7
Correct Answer: A) 4
Rationale: Leading zeros (the zeros before the 5) are not significant. The zeros between the 5 and the
3 are significant because they are between non-zero digits. The trailing zero after the 3 is significant
because there is a decimal point. Significant figures: 5, 0, 3, 0 = 4.
3. Perform the following calculation and report the answer with the correct number of significant
figures: 12.34 × 5.6
A) 69.104
B) 69.10
C) 69
D) 69.1
,Correct Answer: C) 69
Rationale: For multiplication, the result should contain the same number of significant figures as the
measurement with the least number of significant figures. 5.6 has 2 significant figures, so the answer
should have 2 significant figures. 12.34 × 5.6 = 69.104, which rounds to 69.
4. Convert 24.6 grams to kilograms.
A) 0.0246 kg
B) 0.246 kg
C) 2.46 kg
D) 246 kg
Correct Answer: A) 0.0246 kg
Rationale: 1 kg = 1000 g. To convert grams to kilograms, divide by 1000: 24.6 g × (1 kg / 1000 g) =
0.0246 kg. Options B, C, and D result from incorrect decimal placement.
5. Convert 158°F to Celsius.
A) 70°C
B) 126°C
C) 190°C
D) 70°F
Correct Answer: A) 70°C
Rationale: °C = (°F - 32) ÷ 1.8. (158 - 32) ÷ 1.8 = 126 ÷ 1.8 = 70°C. Option B is the result of not dividing
by 1.8, C is from adding 32, and D has the wrong unit.
6. Show the calculation of the mass of an 18.6 mL sample of freon with density 1.49 g/mL.
A) 12.5 g
B) 27.7 g
C) 27.71 g
D) 18.6 g
Correct Answer: B) 27.7 g
, Rationale: Mass = Density × Volume = 1.49 g/mL × 18.6 mL = 27.714 g. With 3 significant figures (1.49
has 3, 18.6 has 3), the answer is 27.7 g. Option A results from dividing, C has too many significant
figures, and D is the volume.
7. Which of the following is a homogeneous mixture?
A) Sand and water
B) Salt water
C) Oil and water
D) Granite
Correct Answer: B) Salt water
Rationale: Salt water is a homogeneous mixture (solution) because the salt is uniformly dissolved and
the composition is the same throughout. Sand and water (A) is heterogeneous, oil and water (C) is
heterogeneous, and granite (D) is a heterogeneous mixture of minerals.
8. Which of the following is an example of a chemical change?
A) Melting ice
B) Boiling water
C) Rusting iron
D) Dissolving sugar in water
Correct Answer: C) Rusting iron
Rationale: Rusting iron is a chemical change because iron reacts with oxygen to form a new substance
(iron oxide). Melting ice (A), boiling water (B), and dissolving sugar in water (D) are physical changes.
9. An atom has 17 protons and 20 neutrons. What is its mass number?
A) 17
B) 20
C) 37
D) 54
Correct Answer: C) 37
Rationale: Mass number = protons + neutrons = 17 + 20 = 37. Option A is the atomic number, B is the
neutron number, and D is the sum including electrons incorrectly.
General Chemistry I-Portage - (26/27) Actual
(PDF)
1. Convert 0.000450 to exponential (scientific notation) form.
A) 4.50 × 10⁻⁴
B) 4.50 × 10⁴
C) 45.0 × 10⁻⁵
D) 0.450 × 10⁻³
Correct Answer: A) 4.50 × 10⁻⁴
Rationale: Move the decimal point 4 places to the right to place it after the first non-zero digit (4.50).
Since the original number is smaller than 1, the exponent is negative. Option B has the wrong
exponent sign, C has two digits before the decimal, and D has zero before the decimal.
2. How many significant figures are in the measurement 0.005030?
A) 4
B) 5
C) 6
D) 7
Correct Answer: A) 4
Rationale: Leading zeros (the zeros before the 5) are not significant. The zeros between the 5 and the
3 are significant because they are between non-zero digits. The trailing zero after the 3 is significant
because there is a decimal point. Significant figures: 5, 0, 3, 0 = 4.
3. Perform the following calculation and report the answer with the correct number of significant
figures: 12.34 × 5.6
A) 69.104
B) 69.10
C) 69
D) 69.1
,Correct Answer: C) 69
Rationale: For multiplication, the result should contain the same number of significant figures as the
measurement with the least number of significant figures. 5.6 has 2 significant figures, so the answer
should have 2 significant figures. 12.34 × 5.6 = 69.104, which rounds to 69.
4. Convert 24.6 grams to kilograms.
A) 0.0246 kg
B) 0.246 kg
C) 2.46 kg
D) 246 kg
Correct Answer: A) 0.0246 kg
Rationale: 1 kg = 1000 g. To convert grams to kilograms, divide by 1000: 24.6 g × (1 kg / 1000 g) =
0.0246 kg. Options B, C, and D result from incorrect decimal placement.
5. Convert 158°F to Celsius.
A) 70°C
B) 126°C
C) 190°C
D) 70°F
Correct Answer: A) 70°C
Rationale: °C = (°F - 32) ÷ 1.8. (158 - 32) ÷ 1.8 = 126 ÷ 1.8 = 70°C. Option B is the result of not dividing
by 1.8, C is from adding 32, and D has the wrong unit.
6. Show the calculation of the mass of an 18.6 mL sample of freon with density 1.49 g/mL.
A) 12.5 g
B) 27.7 g
C) 27.71 g
D) 18.6 g
Correct Answer: B) 27.7 g
, Rationale: Mass = Density × Volume = 1.49 g/mL × 18.6 mL = 27.714 g. With 3 significant figures (1.49
has 3, 18.6 has 3), the answer is 27.7 g. Option A results from dividing, C has too many significant
figures, and D is the volume.
7. Which of the following is a homogeneous mixture?
A) Sand and water
B) Salt water
C) Oil and water
D) Granite
Correct Answer: B) Salt water
Rationale: Salt water is a homogeneous mixture (solution) because the salt is uniformly dissolved and
the composition is the same throughout. Sand and water (A) is heterogeneous, oil and water (C) is
heterogeneous, and granite (D) is a heterogeneous mixture of minerals.
8. Which of the following is an example of a chemical change?
A) Melting ice
B) Boiling water
C) Rusting iron
D) Dissolving sugar in water
Correct Answer: C) Rusting iron
Rationale: Rusting iron is a chemical change because iron reacts with oxygen to form a new substance
(iron oxide). Melting ice (A), boiling water (B), and dissolving sugar in water (D) are physical changes.
9. An atom has 17 protons and 20 neutrons. What is its mass number?
A) 17
B) 20
C) 37
D) 54
Correct Answer: C) 37
Rationale: Mass number = protons + neutrons = 17 + 20 = 37. Option A is the atomic number, B is the
neutron number, and D is the sum including electrons incorrectly.
