1
CHEM 103 Module 1 to 6 Actual Exam
2026/2027 with Verified Answers | Portage
Learning Latest Update | Pass
Guaranteed - A+ Graded
Module 1: Measurements, Significant Figures, and Unit Conversions
Questions 1-20
Question 1 How many significant figures are in the measurement 0.003040 kg?
A. 3 B. 4 [CORRECT] C. 5 D. 6
Correct Answer: B
Rationale:
• Leading zeros (0.00) are NEVER significant - they only locate the decimal point
• The digits 3, 0, 4 are significant (captive zero between non-zero digits is significant)
• The trailing zero after the 4 IS significant because it comes after the decimal point and
after non-zero digits
• Therefore: 3, 0, 4, 0 = 4 significant figures
Why distractors are wrong:
• A (3): Ignores the significant trailing zero after the 4
• C (5): Incorrectly counts one leading zero as significant
• D (6): Counts all digits including the three leading zeros
Question 2 Convert 25.0°C to Kelvin.
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A. 248.2 K B. 273.2 K C. 298.2 K [CORRECT] D. 313.2 K
Correct Answer: C
Rationale:
• Formula: K = °C + 273.15
• Calculation: 25.0 + 273.15 = 298.15 K
• Round to one decimal place to match 25.0°C: 298.2 K
Why distractors are wrong:
• A (248.2): Subtracts 273 instead of adding (25.0 - 273.15 = -248.15)
• B (273.2): This is 0°C in Kelvin, not 25.0°C
• D (313.2): Adds 288.2 instead of 273.15
Question 3 Express 0.000456 in scientific notation.
A. 4.56 × 10⁻³ B. 4.56 × 10⁻⁴ [CORRECT] C. 45.6 × 10⁻⁵ D. 0.456 × 10⁻³
Correct Answer: B
Rationale:
• Scientific notation requires format: a × 10ⁿ where 1 ≤ a < 10
• Move decimal point 4 places to the right: 0.000456 → 4.56
• Since we moved right, exponent is negative: 4.56 × 10⁻⁴
Why distractors are wrong:
• A (4.56 × 10⁻³): Only moved decimal 3 places, not 4
• C (45.6 × 10⁻⁵): 45.6 is not between 1 and 10 (improper format)
• D (0.456 × 10⁻³): 0.456 is not between 1 and 10 (improper format)
Question 4 A substance has a mass of 45.2 g and occupies 38.0 mL. What is its density?
A. 0.841 g/mL B. 1.19 g/mL [CORRECT] C. 1.189 g/mL D. 1720 g/mL
Correct Answer: B
Rationale:
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• Formula: Density = Mass / Volume
• Calculation: 45.2 g / 38.0 mL = 1.18947... g/mL
• For significant figures: 45.2 has 3 sig figs, 38.0 has 3 sig figs
• Answer must have 3 sig figs: 1.19 g/mL
Why distractors are wrong:
• A (0.841): Inverted calculation (38.0/45.2)
• C (1.189): Has 4 sig figs (doesn't match least precise measurement)
• D (1720): Multiplied instead of divided (45.2 × 38.0)
Question 5 How many milligrams are in 2.50 kg?
A. 2.50 mg B. 250 mg C. 2,500,000 mg [CORRECT] D. 0.00250 mg
Correct Answer: C
Rationale:
• Conversion factors: 1 kg = 1000 g and 1 g = 1000 mg
• Therefore: 1 kg = 1,000,000 mg (10⁶ mg)
• Calculation: 2.50 kg × (1000 g/kg) × (1000 mg/g) = 2,500,000 mg or 2.50 × 10⁶ mg
Why distractors are wrong:
• A (2.50): No conversion performed
• B (250): Only converted kg to g (×1000), forgot g to mg
• D (0.00250): Divided instead of multiplied
Question 6 Convert 68°F to Celsius.
A. 20.0°C [CORRECT] B. 36.0°C C. 154.4°C D. 293°C
Correct Answer: A
Rationale:
• Formula: °C = (°F - 32) × 5/9
• Calculation: (68 - 32) × 5/9 = 36 × 5/9 = 180/9 = 20.0°C
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Why distractors are wrong:
• B (36.0): Subtracted 32 but didn't multiply by 5/9
• C (154.4): Added 32 instead of subtracting, then used wrong formula
• D (293): Converted to Kelvin instead of Celsius (68 + 273 = 341, then wrong calc)
Question 7 Perform the calculation: 12.34 + 1.2 - 0.05 = ? (Report with correct significant
figures)
A. 13.49 B. 13.5 [CORRECT] C. 13.50 D. 13
Correct Answer: B
Rationale:
• For addition/subtraction: answer must match the least number of decimal places
• 12.34 has 2 decimal places
• 1.2 has 1 decimal place (limiting term)
• 0.05 has 2 decimal places
• Calculation: 12.34 + 1.2 = 13.54; 13.54 - 0.05 = 13.49
• Round to 1 decimal place: 13.5
Why distractors are wrong:
• A (13.49): Has 2 decimal places (doesn't match limiting term)
• C (13.50): Has 2 decimal places and incorrect rounding
• D (13): Too few significant figures (loses precision)
Question 8 A student measures the density of a liquid as 0.85 g/mL. The accepted value is 0.80
g/mL. What is the percent error?
A. 5.9% B. 6.25% [CORRECT] C. 6.3% D. 6.7%
Correct Answer: B
Rationale:
• Formula: % Error = |Experimental - Accepted| / Accepted × 100%
• Calculation: |0.85 - 0.80| / 0.80 × 100% = 0..80 × 100% = 6.25%
CHEM 103 Module 1 to 6 Actual Exam
2026/2027 with Verified Answers | Portage
Learning Latest Update | Pass
Guaranteed - A+ Graded
Module 1: Measurements, Significant Figures, and Unit Conversions
Questions 1-20
Question 1 How many significant figures are in the measurement 0.003040 kg?
A. 3 B. 4 [CORRECT] C. 5 D. 6
Correct Answer: B
Rationale:
• Leading zeros (0.00) are NEVER significant - they only locate the decimal point
• The digits 3, 0, 4 are significant (captive zero between non-zero digits is significant)
• The trailing zero after the 4 IS significant because it comes after the decimal point and
after non-zero digits
• Therefore: 3, 0, 4, 0 = 4 significant figures
Why distractors are wrong:
• A (3): Ignores the significant trailing zero after the 4
• C (5): Incorrectly counts one leading zero as significant
• D (6): Counts all digits including the three leading zeros
Question 2 Convert 25.0°C to Kelvin.
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A. 248.2 K B. 273.2 K C. 298.2 K [CORRECT] D. 313.2 K
Correct Answer: C
Rationale:
• Formula: K = °C + 273.15
• Calculation: 25.0 + 273.15 = 298.15 K
• Round to one decimal place to match 25.0°C: 298.2 K
Why distractors are wrong:
• A (248.2): Subtracts 273 instead of adding (25.0 - 273.15 = -248.15)
• B (273.2): This is 0°C in Kelvin, not 25.0°C
• D (313.2): Adds 288.2 instead of 273.15
Question 3 Express 0.000456 in scientific notation.
A. 4.56 × 10⁻³ B. 4.56 × 10⁻⁴ [CORRECT] C. 45.6 × 10⁻⁵ D. 0.456 × 10⁻³
Correct Answer: B
Rationale:
• Scientific notation requires format: a × 10ⁿ where 1 ≤ a < 10
• Move decimal point 4 places to the right: 0.000456 → 4.56
• Since we moved right, exponent is negative: 4.56 × 10⁻⁴
Why distractors are wrong:
• A (4.56 × 10⁻³): Only moved decimal 3 places, not 4
• C (45.6 × 10⁻⁵): 45.6 is not between 1 and 10 (improper format)
• D (0.456 × 10⁻³): 0.456 is not between 1 and 10 (improper format)
Question 4 A substance has a mass of 45.2 g and occupies 38.0 mL. What is its density?
A. 0.841 g/mL B. 1.19 g/mL [CORRECT] C. 1.189 g/mL D. 1720 g/mL
Correct Answer: B
Rationale:
,3
• Formula: Density = Mass / Volume
• Calculation: 45.2 g / 38.0 mL = 1.18947... g/mL
• For significant figures: 45.2 has 3 sig figs, 38.0 has 3 sig figs
• Answer must have 3 sig figs: 1.19 g/mL
Why distractors are wrong:
• A (0.841): Inverted calculation (38.0/45.2)
• C (1.189): Has 4 sig figs (doesn't match least precise measurement)
• D (1720): Multiplied instead of divided (45.2 × 38.0)
Question 5 How many milligrams are in 2.50 kg?
A. 2.50 mg B. 250 mg C. 2,500,000 mg [CORRECT] D. 0.00250 mg
Correct Answer: C
Rationale:
• Conversion factors: 1 kg = 1000 g and 1 g = 1000 mg
• Therefore: 1 kg = 1,000,000 mg (10⁶ mg)
• Calculation: 2.50 kg × (1000 g/kg) × (1000 mg/g) = 2,500,000 mg or 2.50 × 10⁶ mg
Why distractors are wrong:
• A (2.50): No conversion performed
• B (250): Only converted kg to g (×1000), forgot g to mg
• D (0.00250): Divided instead of multiplied
Question 6 Convert 68°F to Celsius.
A. 20.0°C [CORRECT] B. 36.0°C C. 154.4°C D. 293°C
Correct Answer: A
Rationale:
• Formula: °C = (°F - 32) × 5/9
• Calculation: (68 - 32) × 5/9 = 36 × 5/9 = 180/9 = 20.0°C
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Why distractors are wrong:
• B (36.0): Subtracted 32 but didn't multiply by 5/9
• C (154.4): Added 32 instead of subtracting, then used wrong formula
• D (293): Converted to Kelvin instead of Celsius (68 + 273 = 341, then wrong calc)
Question 7 Perform the calculation: 12.34 + 1.2 - 0.05 = ? (Report with correct significant
figures)
A. 13.49 B. 13.5 [CORRECT] C. 13.50 D. 13
Correct Answer: B
Rationale:
• For addition/subtraction: answer must match the least number of decimal places
• 12.34 has 2 decimal places
• 1.2 has 1 decimal place (limiting term)
• 0.05 has 2 decimal places
• Calculation: 12.34 + 1.2 = 13.54; 13.54 - 0.05 = 13.49
• Round to 1 decimal place: 13.5
Why distractors are wrong:
• A (13.49): Has 2 decimal places (doesn't match limiting term)
• C (13.50): Has 2 decimal places and incorrect rounding
• D (13): Too few significant figures (loses precision)
Question 8 A student measures the density of a liquid as 0.85 g/mL. The accepted value is 0.80
g/mL. What is the percent error?
A. 5.9% B. 6.25% [CORRECT] C. 6.3% D. 6.7%
Correct Answer: B
Rationale:
• Formula: % Error = |Experimental - Accepted| / Accepted × 100%
• Calculation: |0.85 - 0.80| / 0.80 × 100% = 0..80 × 100% = 6.25%
