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Stoichiometry: Introduction Practice Tests

These Grade 10 Science practice tests introduce moles, Avogadro constant, molar mass, particle and mass conversions, balanced-equation mole ratios, limiting reactants, theoretical yield, percent yield, and empirical formulas.

Skills covered

  • Using the mole as a counting unit and applying Avogadro constant to particles and formula units
  • Calculating molar mass from chemical formulas and converting among grams, moles, and particles
  • Reading balanced-equation coefficients as mole ratios and solving introductory reaction-amount problems
  • Identifying limiting and excess reactants and calculating theoretical and percent yield
  • Using composition data to determine empirical and molecular formulas

How to use these practice tests

Write the balanced equation, identify the known and unknown units, and use dimensional analysis. Keep units visible, use molar mass for grams-to-moles conversion, and use coefficients only after the equation is balanced.

For more Grade 10 Science practice, return to the Grade 10 Science category.

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Grade 10 Stoichiometry Introduction Practice Tests

Practice Grade 10 Science questions about moles, Avogadro constant, molar mass, particle and mass conversions, mole ratios, limiting reactants, yield, and empirical formulas.

Choose the best answer. Track units through mole conversions, use balanced-equation ratios, calculate molar mass, and identify limiting or excess reactants.

10 Questions
0/10 Questions0 %
Correct 0
Incorrect 0
Unanswered 10
1. QuestionMultiple choice

For 2H₂ + O₂ → 2H₂O, what is the mole ratio H₂:O₂?

Please select an answer first.

Correct answer: A

The correct answer is 2:1.

  1. Identify the stoichiometric quantity: Determine whether the question asks about moles, particles, molar mass, a mole ratio, yield, or a limiting reactant.
  2. Set up the relationship: The coefficients show that 2 mol H₂ react with 1 mol O₂.
  3. Check the units and result: The correct answer is 2:1.

The coefficients show that 2 mol H₂ react with 1 mol O₂.

2. QuestionMultiple choice

For N₂ + 3H₂ → 2NH₃, what is the mole ratio H₂:NH₃?

Please select an answer first.

Correct answer: B

The correct answer is 3:2.

  1. Identify the stoichiometric quantity: Determine whether the question asks about moles, particles, molar mass, a mole ratio, yield, or a limiting reactant.
  2. Set up the relationship: The coefficients show that 3 mol H₂ produce 2 mol NH₃.
  3. Check the units and result: The correct answer is 3:2.

The coefficients show that 3 mol H₂ produce 2 mol NH₃.

3. QuestionMultiple choice

For CH₄ + 2O₂ → CO₂ + 2H₂O, how many moles of water form from 1.00 mol CH₄?

Please select an answer first.

Correct answer: C

The correct answer is 2.00 mol H₂O.

  1. Identify the stoichiometric quantity: Determine whether the question asks about moles, particles, molar mass, a mole ratio, yield, or a limiting reactant.
  2. Set up the relationship: The balanced equation gives a 1:2 mole ratio of CH₄ to H₂O.
  3. Check the units and result: The correct answer is 2.00 mol H₂O.

The balanced equation gives a 1:2 mole ratio of CH₄ to H₂O.

4. QuestionMultiple choice

For 2KClO₃ → 2KCl + 3O₂, how many moles of O₂ form from 2.00 mol KClO₃?

Please select an answer first.

Correct answer: D

The correct answer is 3.00 mol O₂.

  1. Identify the stoichiometric quantity: Determine whether the question asks about moles, particles, molar mass, a mole ratio, yield, or a limiting reactant.
  2. Set up the relationship: The coefficient ratio is 2 mol KClO₃ to 3 mol O₂.
  3. Check the units and result: The correct answer is 3.00 mol O₂.

The coefficient ratio is 2 mol KClO₃ to 3 mol O₂.

5. QuestionMultiple choice

What do coefficients in a balanced equation represent in stoichiometry?

Please select an answer first.

Correct answer: A

The correct answer is Relative mole amounts of the substances.

  1. Identify the stoichiometric quantity: Determine whether the question asks about moles, particles, molar mass, a mole ratio, yield, or a limiting reactant.
  2. Set up the relationship: Coefficients establish mole ratios, not the mass of every particular sample.
  3. Check the units and result: The correct answer is Relative mole amounts of the substances.

Coefficients establish mole ratios, not the mass of every particular sample.

6. QuestionMultiple choice

For 2H₂ + O₂ → 2H₂O, how many moles of H₂O form from 4.00 mol H₂ with excess oxygen?

Please select an answer first.

Correct answer: B

The correct answer is 4.00 mol H₂O.

  1. Identify the stoichiometric quantity: Determine whether the question asks about moles, particles, molar mass, a mole ratio, yield, or a limiting reactant.
  2. Set up the relationship: The H₂:H₂O ratio is 2:2, so 4.00 mol H₂ produces 4.00 mol H₂O.
  3. Check the units and result: The correct answer is 4.00 mol H₂O.

The H₂:H₂O ratio is 2:2, so 4.00 mol H₂ produces 4.00 mol H₂O.

7. QuestionMultiple choice

For N₂ + 3H₂ → 2NH₃, how many moles of NH₃ form from 0.500 mol N₂ with excess H₂?

Please select an answer first.

Correct answer: C

The correct answer is 1.00 mol NH₃.

  1. Identify the stoichiometric quantity: Determine whether the question asks about moles, particles, molar mass, a mole ratio, yield, or a limiting reactant.
  2. Set up the relationship: The N₂:NH₃ ratio is 1:2, so 0.500 mol N₂ produces 1.00 mol NH₃.
  3. Check the units and result: The correct answer is 1.00 mol NH₃.

The N₂:NH₃ ratio is 1:2, so 0.500 mol N₂ produces 1.00 mol NH₃.

8. QuestionMultiple choice

For C₃H₈ + 5O₂ → 3CO₂ + 4H₂O, how many moles of CO₂ form from 3.00 mol O₂ with excess propane?

Please select an answer first.

Correct answer: D

The correct answer is 1.80 mol CO₂.

  1. Identify the stoichiometric quantity: Determine whether the question asks about moles, particles, molar mass, a mole ratio, yield, or a limiting reactant.
  2. Set up the relationship: Use 3 mol O₂ × 3 mol CO₂ ÷ 5 mol O₂ = 1.80 mol CO₂.
  3. Check the units and result: The correct answer is 1.80 mol CO₂.

Use 3 mol O₂ × 3 mol CO₂ ÷ 5 mol O₂ = 1.80 mol CO₂.

9. QuestionMultiple choice

Which ratio can be used to convert moles of N₂ to moles of NH₃ in N₂ + 3H₂ → 2NH₃?

Please select an answer first.

Correct answer: A

The correct answer is 2 mol NH₃ / 1 mol N₂.

  1. Identify the stoichiometric quantity: Determine whether the question asks about moles, particles, molar mass, a mole ratio, yield, or a limiting reactant.
  2. Set up the relationship: The coefficients provide the conversion factor 2 mol NH₃ for every 1 mol N₂.
  3. Check the units and result: The correct answer is 2 mol NH₃ / 1 mol N₂.

The coefficients provide the conversion factor 2 mol NH₃ for every 1 mol N₂.

10. QuestionMultiple choice

What is the standard stoichiometry pathway from mass of a reactant to mass of a product?

Please select an answer first.

Correct answer: B

The correct answer is Mass to moles, mole ratio, then moles to mass.

  1. Identify the stoichiometric quantity: Determine whether the question asks about moles, particles, molar mass, a mole ratio, yield, or a limiting reactant.
  2. Set up the relationship: Molar mass and the balanced-equation mole ratio connect the two masses.
  3. Check the units and result: The correct answer is Mass to moles, mole ratio, then moles to mass.

Molar mass and the balanced-equation mole ratio connect the two masses.

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