,CHEM 103 FINAL Exam | General Chemistry I
w/Lab | Portage Learning | Q & A | 2026
Edition
1. Which of the following values represents the number 0.000451 correctly expressed in scientific
notation?
A) 4.51 × 10⁻⁴
B) 45.1 × 10⁻⁵
C) 4.51 × 10⁴
D) 0.451 × 10⁻³
Correct Answer: 4.51 × 10⁻⁴
Rationale: To convert a number less than 1 into scientific notation, the decimal point moves to the right
until it is placed after the first nonzero digit. For 0.000451, the decimal moves 4 places to the right to get
4.51. Because the original number is less than 1, the exponent must be negative, resulting in 4.51 × 10⁻⁴.
2. Convert 845.3 to exponential form.
A) 8.453 × 10²
B) 84.53 × 10¹
C) 8.453 × 10³
D) 0.8453 × 10³
Correct Answer: 8.453 × 10²
Rationale: 845.3 is larger than 1, so the exponent is positive. Move the decimal 2 places to the left to get
a number between 1 and 10, resulting in 8.453 × 10².
3. Convert 3.21 × 10⁻⁵ to ordinary form.
A) 0.0000321
,B) 0.000321
C) 321,000
D) 0.00000321
Correct Answer: 0.0000321
Rationale: A negative exponent indicates the number is smaller than 1. Move the decimal 5 places to the
left: 3.21 × 10⁻⁵ = 0.0000321.
4. Convert 28°C to kelvin.
A) 301 K
B) 245 K
C) 55 K
D) 301°C
Correct Answer: 301 K
Rationale: The conversion from Celsius to kelvin is K = °C + 273. For 28°C: 28 + 273 = 301 K.
5. Convert 158°F to degrees Celsius.
A) 70°C
B) 316°C
C) 126°C
D) 70°F
Correct Answer: 70°C
Rationale: The conversion formula is °C = (°F − 32) ÷ 1.8. For 158°F: (158 − 32) ÷ 1.8 = 126 ÷ 1.8 = 70°C.
, 6. Convert 343 K to degrees Fahrenheit.
A) 158°F
B) 70°F
C) 617°F
D) 158°C
Correct Answer: 158°F
Rationale: First convert K to °C: 343 − 273 = 70°C. Then convert °C to °F: (70 × 1.8) + 32 = 126 + 32 =
158°F.
7. Show the calculation of the mass of an 18.6 mL sample of freon with a density of 1.49 g/mL.
A) 27.7 g
B) 12.5 g
C) 27.7 mL
D) 20.1 g
Correct Answer: 27.7 g
Rationale: Mass = Density × Volume. M = 1.49 g/mL × 18.6 mL = 27.7 g. The answer must be reported
with the correct number of significant figures.
8. Show the calculation of the density of crude oil if 26.3 g occupies 30.5 mL.
A) 0.862 g/mL
B) 1.16 g/mL
C) 0.862 mL/g
D) 26.3 g/mL
Correct Answer: 0.862 g/mL
w/Lab | Portage Learning | Q & A | 2026
Edition
1. Which of the following values represents the number 0.000451 correctly expressed in scientific
notation?
A) 4.51 × 10⁻⁴
B) 45.1 × 10⁻⁵
C) 4.51 × 10⁴
D) 0.451 × 10⁻³
Correct Answer: 4.51 × 10⁻⁴
Rationale: To convert a number less than 1 into scientific notation, the decimal point moves to the right
until it is placed after the first nonzero digit. For 0.000451, the decimal moves 4 places to the right to get
4.51. Because the original number is less than 1, the exponent must be negative, resulting in 4.51 × 10⁻⁴.
2. Convert 845.3 to exponential form.
A) 8.453 × 10²
B) 84.53 × 10¹
C) 8.453 × 10³
D) 0.8453 × 10³
Correct Answer: 8.453 × 10²
Rationale: 845.3 is larger than 1, so the exponent is positive. Move the decimal 2 places to the left to get
a number between 1 and 10, resulting in 8.453 × 10².
3. Convert 3.21 × 10⁻⁵ to ordinary form.
A) 0.0000321
,B) 0.000321
C) 321,000
D) 0.00000321
Correct Answer: 0.0000321
Rationale: A negative exponent indicates the number is smaller than 1. Move the decimal 5 places to the
left: 3.21 × 10⁻⁵ = 0.0000321.
4. Convert 28°C to kelvin.
A) 301 K
B) 245 K
C) 55 K
D) 301°C
Correct Answer: 301 K
Rationale: The conversion from Celsius to kelvin is K = °C + 273. For 28°C: 28 + 273 = 301 K.
5. Convert 158°F to degrees Celsius.
A) 70°C
B) 316°C
C) 126°C
D) 70°F
Correct Answer: 70°C
Rationale: The conversion formula is °C = (°F − 32) ÷ 1.8. For 158°F: (158 − 32) ÷ 1.8 = 126 ÷ 1.8 = 70°C.
, 6. Convert 343 K to degrees Fahrenheit.
A) 158°F
B) 70°F
C) 617°F
D) 158°C
Correct Answer: 158°F
Rationale: First convert K to °C: 343 − 273 = 70°C. Then convert °C to °F: (70 × 1.8) + 32 = 126 + 32 =
158°F.
7. Show the calculation of the mass of an 18.6 mL sample of freon with a density of 1.49 g/mL.
A) 27.7 g
B) 12.5 g
C) 27.7 mL
D) 20.1 g
Correct Answer: 27.7 g
Rationale: Mass = Density × Volume. M = 1.49 g/mL × 18.6 mL = 27.7 g. The answer must be reported
with the correct number of significant figures.
8. Show the calculation of the density of crude oil if 26.3 g occupies 30.5 mL.
A) 0.862 g/mL
B) 1.16 g/mL
C) 0.862 mL/g
D) 26.3 g/mL
Correct Answer: 0.862 g/mL
