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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

What is the approximate molar mass of CO₂?

Please select an answer first.

Correct answer: A

The correct answer is 44.0 g/mol.

  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: One carbon contributes about 12.0 g/mol and two oxygens contribute about 32.0 g/mol.
  3. Check the units and result: The correct answer is 44.0 g/mol.

One carbon contributes about 12.0 g/mol and two oxygens contribute about 32.0 g/mol.

2. QuestionMultiple choice

What is the approximate molar mass of NaCl?

Please select an answer first.

Correct answer: B

The correct answer is 58.5 g/mol.

  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: Add sodium about 23.0 g/mol and chlorine about 35.5 g/mol.
  3. Check the units and result: The correct answer is 58.5 g/mol.

Add sodium about 23.0 g/mol and chlorine about 35.5 g/mol.

3. QuestionMultiple choice

What is the approximate molar mass of CaCO₃?

Please select an answer first.

Correct answer: C

The correct answer is 100.1 g/mol.

  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: Calcium, carbon, and three oxygen atoms total about 100.1 g/mol.
  3. Check the units and result: The correct answer is 100.1 g/mol.

Calcium, carbon, and three oxygen atoms total about 100.1 g/mol.

4. QuestionMultiple choice

What is the approximate molar mass of H₂SO₄?

Please select an answer first.

Correct answer: D

The correct answer is 98.1 g/mol.

  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: Two hydrogen, one sulfur, and four oxygen atoms total about 98.1 g/mol.
  3. Check the units and result: The correct answer is 98.1 g/mol.

Two hydrogen, one sulfur, and four oxygen atoms total about 98.1 g/mol.

5. QuestionMultiple choice

What is the mass of 2.00 mol of O₂?

Please select an answer first.

Correct answer: A

The correct answer is 64.0 g.

  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: O₂ has a molar mass of 32.0 g/mol, so 2.00 mol has a mass of 64.0 g.
  3. Check the units and result: The correct answer is 64.0 g.

O₂ has a molar mass of 32.0 g/mol, so 2.00 mol has a mass of 64.0 g.

6. QuestionMultiple choice

What is the mass of 0.500 mol of CO₂?

Please select an answer first.

Correct answer: B

The correct answer is 22.0 g.

  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: Multiply 0.500 mol by the CO₂ molar mass of 44.0 g/mol.
  3. Check the units and result: The correct answer is 22.0 g.

Multiply 0.500 mol by the CO₂ molar mass of 44.0 g/mol.

7. QuestionMultiple choice

How many moles are in 18.0 g of H₂O?

Please select an answer first.

Correct answer: C

The correct answer is 1.00 mol.

  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: Divide 18.0 g by the H₂O molar mass of 18.0 g/mol.
  3. Check the units and result: The correct answer is 1.00 mol.

Divide 18.0 g by the H₂O molar mass of 18.0 g/mol.

8. QuestionMultiple choice

How many moles are in 36.0 g of H₂O?

Please select an answer first.

Correct answer: D

The correct answer is 2.00 mol.

  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: Divide 36.0 g by 18.0 g/mol to obtain 2.00 mol.
  3. Check the units and result: The correct answer is 2.00 mol.

Divide 36.0 g by 18.0 g/mol to obtain 2.00 mol.

9. QuestionMultiple choice

What is the molar mass of a compound with formula NH₃ approximately?

Please select an answer first.

Correct answer: A

The correct answer is 17.0 g/mol.

  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: Nitrogen contributes about 14.0 g/mol and three hydrogens contribute about 3.0 g/mol.
  3. Check the units and result: The correct answer is 17.0 g/mol.

Nitrogen contributes about 14.0 g/mol and three hydrogens contribute about 3.0 g/mol.

10. QuestionMultiple choice

What is the first step when calculating molar mass from a formula?

Please select an answer first.

Correct answer: B

The correct answer is Multiply each element atomic mass by its subscript and add the results..

  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: Subscripts show how many atoms of each element contribute to the formula mass.
  3. Check the units and result: The correct answer is Multiply each element atomic mass by its subscript and add the results..

Subscripts show how many atoms of each element contribute to the formula mass.

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