Exam: Portage Learning CHEM 103 General
Chemistry I Module 4 Exam | 2026/2027 Updated
Edition with 100% Verified Answers
Q1 Balance the following equation and determine the sum of the coefficients once...
Balance the following equation and determine the sum of the coefficients once balanced: C₃H₈ +
O₂ → CO₂ + H₂O
A) 11
B) 12
C) 13 CORRECT
D) 14
Rationale
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O. Coefficients: 1 + 5 + 3 + 4 = 13 .
Q2 How many moles of oxygen gas are required to completely burn 2.5 moles of...
How many moles of oxygen gas are required to completely burn 2.5 moles of propane (C₃H₈)?
A) 2.5 mol
B) 5.0 mol
C) 7.5 mol
D) 12.5 mol CORRECT
Rationale
From the balanced equation, 1 mol C₃H₈ requires 5 mol O₂. 2.5 × 5 = 12.5 mol O₂ .
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,Q3 What mass (in grams) of carbon dioxide is produced
What mass (in grams) of carbon dioxide is produced when 44.0 g of propane undergoes complete
combustion? (Molar masses: C₃H₈ = 44.1 g/mol, CO₂ = 44.0 g/mol)
A) 44.0 g
B) 88.0 g
C) 132 g CORRECT
D) 176 g
Rationale
Moles C₃H₈ ≈ 1.00 mol. From equation, 1 mol C₃H₈ → 3 mol CO₂. Mass CO₂ = 3 × 44.0 = 132 g .
Q4 When solid sodium chloride is added to a solution of silver nitrate, a white...
When solid sodium chloride is added to a solution of silver nitrate, a white precipitate forms.
Write the net ionic equation for this reaction.
A) Na⁺(aq) + Cl⁻(aq) → NaCl(s)
B) Ag⁺(aq) + NO₃⁻(aq) → AgNO₃(s)
C) Ag⁺(aq) + Cl⁻(aq) → AgCl(s) CORRECT
D) Na⁺(aq) + NO₃⁻(aq) → NaNO₃(s)
Rationale
NaCl(aq) + AgNO₃(aq) → AgCl(s) + NaNO₃(aq). Silver and chloride ions form the precipitate; sodium and
nitrate are spectator ions .
Q5 A student reacts 5.00 g of Fe₂O₃ with excess CO according to: Fe₂O₃(s) +...
A student reacts 5.00 g of Fe₂O₃ with excess CO according to: Fe₂O₃(s) + 3CO(g) → 2Fe(s) +
3CO₂(g). What is the theoretical yield of iron (Fe)? (Fe₂O₃ = 159.7 g/mol, Fe = 55.85 g/mol)
A) 1.75 g
B) 3.50 g CORRECT
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,C) 5.00 g
D) 7.00 g
Rationale
Moles Fe₂O₃ = 5.00/159.7 = 0.0313 mol. 1 mol Fe₂O₃ → 2 mol Fe. Mass Fe = 0.0626 × 55.85 ≈ 3.50 g .
Q6 What is Avogadro's number?
What is Avogadro's number?
A) 6.022 × 10²²
B) 6.022 × 10²³ CORRECT
C) 6.022 × 10²⁴
D) 6.022 × 10²¹
Rationale
Avogadro's number is the number of entities (atoms, molecules, ions) in one mole of a substance, equal
to 6.022 × 10²³ .
Q7 What is the molar mass of a substance?
What is the molar mass of a substance?
A) Mass in grams of 1 atom of the substance
B) Mass in grams of 1 mole of the substance CORRECT
C) Mass in grams of 1 molecule of the substance
D) Mass in kilograms of 1 mole of the substance
Rationale
Molar mass is the mass in grams of one mole of a substance, numerically equal to the formula mass in
atomic mass units .
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, Q8 The formula mass for ionic compounds is determined by:
The formula mass for ionic compounds is determined by:
A) The number of molecules in the compound
B) The ratio of atoms in the compound CORRECT
C) The volume of the compound
D) The density of the compound
Rationale
Formula mass for ionic compounds is determined by the ratio of atoms (stoichiometry), reflecting the
constituent ions and their charges .
Q9 What is the dilution equation?
What is the dilution equation?
A) M₁V₂ = M₂V₁
B) M₁V₁ = M₂V₂ CORRECT
C) M₁V₁ = M₂V₁
D) M₁V₂ = M₂V₂
Rationale
The dilution equation states that moles of solute before dilution equals moles after dilution: M₁V₁ = M₂V₂
(or C₁V₁ = C₂V₂) .
Q10 The formula for mass percentage is:
The formula for mass percentage is:
A) (mass of solute / mass of solvent) × 100%
B) (mass of solute / mass of solution) × 100% CORRECT
C) (mass of solvent / mass of solution) × 100%
D) (mass of solution / mass of solute) × 100%
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Chemistry I Module 4 Exam | 2026/2027 Updated
Edition with 100% Verified Answers
Q1 Balance the following equation and determine the sum of the coefficients once...
Balance the following equation and determine the sum of the coefficients once balanced: C₃H₈ +
O₂ → CO₂ + H₂O
A) 11
B) 12
C) 13 CORRECT
D) 14
Rationale
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O. Coefficients: 1 + 5 + 3 + 4 = 13 .
Q2 How many moles of oxygen gas are required to completely burn 2.5 moles of...
How many moles of oxygen gas are required to completely burn 2.5 moles of propane (C₃H₈)?
A) 2.5 mol
B) 5.0 mol
C) 7.5 mol
D) 12.5 mol CORRECT
Rationale
From the balanced equation, 1 mol C₃H₈ requires 5 mol O₂. 2.5 × 5 = 12.5 mol O₂ .
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,Q3 What mass (in grams) of carbon dioxide is produced
What mass (in grams) of carbon dioxide is produced when 44.0 g of propane undergoes complete
combustion? (Molar masses: C₃H₈ = 44.1 g/mol, CO₂ = 44.0 g/mol)
A) 44.0 g
B) 88.0 g
C) 132 g CORRECT
D) 176 g
Rationale
Moles C₃H₈ ≈ 1.00 mol. From equation, 1 mol C₃H₈ → 3 mol CO₂. Mass CO₂ = 3 × 44.0 = 132 g .
Q4 When solid sodium chloride is added to a solution of silver nitrate, a white...
When solid sodium chloride is added to a solution of silver nitrate, a white precipitate forms.
Write the net ionic equation for this reaction.
A) Na⁺(aq) + Cl⁻(aq) → NaCl(s)
B) Ag⁺(aq) + NO₃⁻(aq) → AgNO₃(s)
C) Ag⁺(aq) + Cl⁻(aq) → AgCl(s) CORRECT
D) Na⁺(aq) + NO₃⁻(aq) → NaNO₃(s)
Rationale
NaCl(aq) + AgNO₃(aq) → AgCl(s) + NaNO₃(aq). Silver and chloride ions form the precipitate; sodium and
nitrate are spectator ions .
Q5 A student reacts 5.00 g of Fe₂O₃ with excess CO according to: Fe₂O₃(s) +...
A student reacts 5.00 g of Fe₂O₃ with excess CO according to: Fe₂O₃(s) + 3CO(g) → 2Fe(s) +
3CO₂(g). What is the theoretical yield of iron (Fe)? (Fe₂O₃ = 159.7 g/mol, Fe = 55.85 g/mol)
A) 1.75 g
B) 3.50 g CORRECT
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,C) 5.00 g
D) 7.00 g
Rationale
Moles Fe₂O₃ = 5.00/159.7 = 0.0313 mol. 1 mol Fe₂O₃ → 2 mol Fe. Mass Fe = 0.0626 × 55.85 ≈ 3.50 g .
Q6 What is Avogadro's number?
What is Avogadro's number?
A) 6.022 × 10²²
B) 6.022 × 10²³ CORRECT
C) 6.022 × 10²⁴
D) 6.022 × 10²¹
Rationale
Avogadro's number is the number of entities (atoms, molecules, ions) in one mole of a substance, equal
to 6.022 × 10²³ .
Q7 What is the molar mass of a substance?
What is the molar mass of a substance?
A) Mass in grams of 1 atom of the substance
B) Mass in grams of 1 mole of the substance CORRECT
C) Mass in grams of 1 molecule of the substance
D) Mass in kilograms of 1 mole of the substance
Rationale
Molar mass is the mass in grams of one mole of a substance, numerically equal to the formula mass in
atomic mass units .
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, Q8 The formula mass for ionic compounds is determined by:
The formula mass for ionic compounds is determined by:
A) The number of molecules in the compound
B) The ratio of atoms in the compound CORRECT
C) The volume of the compound
D) The density of the compound
Rationale
Formula mass for ionic compounds is determined by the ratio of atoms (stoichiometry), reflecting the
constituent ions and their charges .
Q9 What is the dilution equation?
What is the dilution equation?
A) M₁V₂ = M₂V₁
B) M₁V₁ = M₂V₂ CORRECT
C) M₁V₁ = M₂V₁
D) M₁V₂ = M₂V₂
Rationale
The dilution equation states that moles of solute before dilution equals moles after dilution: M₁V₁ = M₂V₂
(or C₁V₁ = C₂V₂) .
Q10 The formula for mass percentage is:
The formula for mass percentage is:
A) (mass of solute / mass of solvent) × 100%
B) (mass of solute / mass of solution) × 100% CORRECT
C) (mass of solvent / mass of solution) × 100%
D) (mass of solution / mass of solute) × 100%
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