CHEM 103 Introduction to General Chemistry
Modules 1–6 Examination, Portage Learning,
2026/2027 – 100-Question Comprehensive
Chemistry Examination with Verified Answers
📝 MODULE 1: MEASUREMENT & SCIENTIFIC NOTATION (Questions 1-
15)
1. Convert 845.3 to exponential form.
A) 8.453 × 10⁻²
B) 8.453 × 10¹
C) 8.453 × 10²
D) 8.453 × 10³
Correct Answer: C
Rationale: 845.3 is greater than 1, so it requires a positive exponent. Moving
the decimal 2 places to the left yields 8.453 × 10² .
2. Convert 3.21 × 10⁻⁵ to ordinary form.
A) 0.0000321
B) 0.000321
C) 321,000
D) 32,100
Correct Answer: A
Rationale: A negative exponent in scientific notation indicates a number
smaller than 1. The exponent -5 means move the decimal 5 places to the
left: 0.0000321 .
3. How many significant figures are in 0.004060?
A) 4
B) 5
C) 6
D) 7
Correct Answer: A
Rationale: Leading zeros are never significant. Captive zeros and trailing
,zeros after a decimal point are significant. 0.004060 has 4 significant figures
(4,0,6,0) .
4. The metric prefix "milli-" represents what power of 10?
A) 10⁻³
B) 10³
C) 10⁻⁶
D) 10⁶
Correct Answer: A
Rationale: Milli- denotes 10⁻³ (0.001). For example, 1 millimeter = 0.001
meter .
5. Convert 25.4 mm to meters.
A) 0.0254 m
B) 0.254 m
C) 2.54 m
D) 25,400 m
Correct Answer: A
Rationale: 1 m = 1000 mm. 25.4 mm ÷ 1000 = 0.0254 m .
6. What is the correct sum of 2.5 × 10³ + 3.2 × 10² expressed in
scientific notation with proper significant figures?
A) 2.82 × 10³
B) 28.2 × 10²
C) 2.82 × 10⁴
D) 2.82 × 10²
Correct Answer: A
Rationale: Align exponents: 2.5 × 10³ = 2500, 3.2 × 10² = 320. Sum = 2820
= 2.82 × 10³ .
7. How many significant figures should be reported for the product
6.02 × 4.10?
A) 2
B) 3
C) 4
D) 5
Correct Answer: B
Rationale: For multiplication, the result should have the same number of
significant figures as the factor with the fewest. Both 6.02 and 4.10 have 3
significant figures, so the product should have 3 .
, 8. 1.6605 × 10⁻²⁷ kg is equivalent to:
A) 1 amu
B) 1 g
C) 1 lb
D) 1 ton
Correct Answer: A
Rationale: 1 atomic mass unit (amu) = 1.6605 × 10⁻²⁷ kg. This is the
standard unit for atomic and molecular masses .
9. The diameter of an atom is approximately:
A) 2 pm
B) 2 Å
C) 2 nm
D) 2 μm
Correct Answer: B
Rationale: The diameter of an atom is approximately 2 Å (angstroms), where
1 Å = 10⁻¹⁰ m .
10. Which of the following is a physical change?
A) Rusting of iron
B) Burning of wood
C) Melting of ice
D) Digestion of food
Correct Answer: C
Rationale: A physical change does not alter the chemical identity of a
substance. Melting ice changes state from solid to liquid, but the chemical
formula (H₂O) remains unchanged .
11. Which of the following is a chemical change?
A) Breaking glass
B) Dissolving sugar in water
C) Burning gasoline in an engine
D) Boiling water
Correct Answer: C
Rationale: A chemical change involves breaking and forming chemical
bonds, creating new substances. Combustion of gasoline produces CO₂ and
H₂O, chemically different from the reactants .
Modules 1–6 Examination, Portage Learning,
2026/2027 – 100-Question Comprehensive
Chemistry Examination with Verified Answers
📝 MODULE 1: MEASUREMENT & SCIENTIFIC NOTATION (Questions 1-
15)
1. Convert 845.3 to exponential form.
A) 8.453 × 10⁻²
B) 8.453 × 10¹
C) 8.453 × 10²
D) 8.453 × 10³
Correct Answer: C
Rationale: 845.3 is greater than 1, so it requires a positive exponent. Moving
the decimal 2 places to the left yields 8.453 × 10² .
2. Convert 3.21 × 10⁻⁵ to ordinary form.
A) 0.0000321
B) 0.000321
C) 321,000
D) 32,100
Correct Answer: A
Rationale: A negative exponent in scientific notation indicates a number
smaller than 1. The exponent -5 means move the decimal 5 places to the
left: 0.0000321 .
3. How many significant figures are in 0.004060?
A) 4
B) 5
C) 6
D) 7
Correct Answer: A
Rationale: Leading zeros are never significant. Captive zeros and trailing
,zeros after a decimal point are significant. 0.004060 has 4 significant figures
(4,0,6,0) .
4. The metric prefix "milli-" represents what power of 10?
A) 10⁻³
B) 10³
C) 10⁻⁶
D) 10⁶
Correct Answer: A
Rationale: Milli- denotes 10⁻³ (0.001). For example, 1 millimeter = 0.001
meter .
5. Convert 25.4 mm to meters.
A) 0.0254 m
B) 0.254 m
C) 2.54 m
D) 25,400 m
Correct Answer: A
Rationale: 1 m = 1000 mm. 25.4 mm ÷ 1000 = 0.0254 m .
6. What is the correct sum of 2.5 × 10³ + 3.2 × 10² expressed in
scientific notation with proper significant figures?
A) 2.82 × 10³
B) 28.2 × 10²
C) 2.82 × 10⁴
D) 2.82 × 10²
Correct Answer: A
Rationale: Align exponents: 2.5 × 10³ = 2500, 3.2 × 10² = 320. Sum = 2820
= 2.82 × 10³ .
7. How many significant figures should be reported for the product
6.02 × 4.10?
A) 2
B) 3
C) 4
D) 5
Correct Answer: B
Rationale: For multiplication, the result should have the same number of
significant figures as the factor with the fewest. Both 6.02 and 4.10 have 3
significant figures, so the product should have 3 .
, 8. 1.6605 × 10⁻²⁷ kg is equivalent to:
A) 1 amu
B) 1 g
C) 1 lb
D) 1 ton
Correct Answer: A
Rationale: 1 atomic mass unit (amu) = 1.6605 × 10⁻²⁷ kg. This is the
standard unit for atomic and molecular masses .
9. The diameter of an atom is approximately:
A) 2 pm
B) 2 Å
C) 2 nm
D) 2 μm
Correct Answer: B
Rationale: The diameter of an atom is approximately 2 Å (angstroms), where
1 Å = 10⁻¹⁰ m .
10. Which of the following is a physical change?
A) Rusting of iron
B) Burning of wood
C) Melting of ice
D) Digestion of food
Correct Answer: C
Rationale: A physical change does not alter the chemical identity of a
substance. Melting ice changes state from solid to liquid, but the chemical
formula (H₂O) remains unchanged .
11. Which of the following is a chemical change?
A) Breaking glass
B) Dissolving sugar in water
C) Burning gasoline in an engine
D) Boiling water
Correct Answer: C
Rationale: A chemical change involves breaking and forming chemical
bonds, creating new substances. Combustion of gasoline produces CO₂ and
H₂O, chemically different from the reactants .
