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Chemical Reactions Practice Tests

These Grade 8 Science practice tests cover chemical and physical changes, reactants, products, evidence of reactions, conservation of mass, balanced equations, coefficients, subscripts, energy changes, catalysts, and reaction types.

Skills covered

  • Distinguishing chemical reactions from physical changes
  • Identifying reactants, products, coefficients, subscripts, and balanced equations
  • Applying conservation of atoms and mass in closed systems
  • Analyzing exothermic and endothermic energy changes and catalysts
  • Recognizing synthesis, decomposition, combustion, replacement, and neutralization patterns

How to use these practice tests

Look for evidence of new substances, identify the starting and ending materials, and count atoms on both sides of an equation. Use coefficients to balance equations without changing subscripts or substance identities.

For more Grade 8 Science practice, return to the Grade 8 Science category.

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1. Test

Grade 8 Chemical Reactions Practice Tests

Practice Grade 8 Science questions about chemical changes, reactants, products, conservation of mass, balanced equations, energy, catalysts, and reaction types.

Choose the best answer for each question. Use observations, atom counts, balanced equations, energy evidence, and reaction patterns to analyze chemical reactions.

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

What is a chemical reaction?

Please select an answer first.

Correct answer: A

The correct answer is A process in which atoms are rearranged to form new substances.

  1. Identify the reaction information: Determine whether the question describes a chemical change, reactant, product, equation, energy change, or reaction pattern.
  2. Track atoms and energy: Count each type of atom, distinguish coefficients from subscripts, and compare energy before and after the reaction.
  3. Check the evidence: Use observations such as gas, precipitate, temperature, color, or new odor together with conservation and balanced equations.

Chemical reactions rearrange atoms and produce substances with new combinations and properties.

2. QuestionMultiple choice

What are reactants?

Please select an answer first.

Correct answer: B

The correct answer is The starting substances in a chemical reaction.

  1. Identify the reaction information: Determine whether the question describes a chemical change, reactant, product, equation, energy change, or reaction pattern.
  2. Track atoms and energy: Count each type of atom, distinguish coefficients from subscripts, and compare energy before and after the reaction.
  3. Check the evidence: Use observations such as gas, precipitate, temperature, color, or new odor together with conservation and balanced equations.

Reactants are present before the reaction and are changed into products.

3. QuestionMultiple choice

What are products?

Please select an answer first.

Correct answer: C

The correct answer is The new substances formed by a chemical reaction.

  1. Identify the reaction information: Determine whether the question describes a chemical change, reactant, product, equation, energy change, or reaction pattern.
  2. Track atoms and energy: Count each type of atom, distinguish coefficients from subscripts, and compare energy before and after the reaction.
  3. Check the evidence: Use observations such as gas, precipitate, temperature, color, or new odor together with conservation and balanced equations.

Products are the substances present after atoms have been rearranged.

4. QuestionMultiple choice

Which observation is evidence that a chemical reaction may have occurred?

Please select an answer first.

Correct answer: D

The correct answer is A gas forms when two clear solutions are mixed..

  1. Identify the reaction information: Determine whether the question describes a chemical change, reactant, product, equation, energy change, or reaction pattern.
  2. Track atoms and energy: Count each type of atom, distinguish coefficients from subscripts, and compare energy before and after the reaction.
  3. Check the evidence: Use observations such as gas, precipitate, temperature, color, or new odor together with conservation and balanced equations.

Unexpected gas formation can indicate that a new substance formed, although evidence should be interpreted with other observations.

5. QuestionMultiple choice

Which is a physical change rather than a chemical reaction?

Please select an answer first.

Correct answer: A

The correct answer is Ice melts into liquid water..

  1. Identify the reaction information: Determine whether the question describes a chemical change, reactant, product, equation, energy change, or reaction pattern.
  2. Track atoms and energy: Count each type of atom, distinguish coefficients from subscripts, and compare energy before and after the reaction.
  3. Check the evidence: Use observations such as gas, precipitate, temperature, color, or new odor together with conservation and balanced equations.

Melting changes the state of water but does not create a new substance.

6. QuestionMultiple choice

What is evidence that a new substance formed?

Please select an answer first.

Correct answer: B

The correct answer is The material has new properties that were not present in the starting substances..

  1. Identify the reaction information: Determine whether the question describes a chemical change, reactant, product, equation, energy change, or reaction pattern.
  2. Track atoms and energy: Count each type of atom, distinguish coefficients from subscripts, and compare energy before and after the reaction.
  3. Check the evidence: Use observations such as gas, precipitate, temperature, color, or new odor together with conservation and balanced equations.

New properties such as unexpected gas, precipitate, color, or energy change can support the conclusion of a chemical reaction.

7. QuestionMultiple choice

What happens to atoms during a chemical reaction?

Please select an answer first.

Correct answer: C

The correct answer is They are rearranged into new combinations..

  1. Identify the reaction information: Determine whether the question describes a chemical change, reactant, product, equation, energy change, or reaction pattern.
  2. Track atoms and energy: Count each type of atom, distinguish coefficients from subscripts, and compare energy before and after the reaction.
  3. Check the evidence: Use observations such as gas, precipitate, temperature, color, or new odor together with conservation and balanced equations.

Chemical reactions change how atoms are connected while conserving the atoms and their element identities.

8. QuestionMultiple choice

In a chemical equation, what does the arrow usually mean?

Please select an answer first.

Correct answer: D

The correct answer is Yields or produces.

  1. Identify the reaction information: Determine whether the question describes a chemical change, reactant, product, equation, energy change, or reaction pattern.
  2. Track atoms and energy: Count each type of atom, distinguish coefficients from subscripts, and compare energy before and after the reaction.
  3. Check the evidence: Use observations such as gas, precipitate, temperature, color, or new odor together with conservation and balanced equations.

The arrow separates reactants from products and shows the direction of the reaction representation.

9. QuestionMultiple choice

What does a subscript in a chemical formula show?

Please select an answer first.

Correct answer: A

The correct answer is The number of atoms of an element in one molecule or formula unit.

  1. Identify the reaction information: Determine whether the question describes a chemical change, reactant, product, equation, energy change, or reaction pattern.
  2. Track atoms and energy: Count each type of atom, distinguish coefficients from subscripts, and compare energy before and after the reaction.
  3. Check the evidence: Use observations such as gas, precipitate, temperature, color, or new odor together with conservation and balanced equations.

A subscript belongs to the element symbol before it and gives the atom count in that particle.

10. QuestionMultiple choice

What does a coefficient in front of a chemical formula show?

Please select an answer first.

Correct answer: B

The correct answer is The number of molecules or formula units involved.

  1. Identify the reaction information: Determine whether the question describes a chemical change, reactant, product, equation, energy change, or reaction pattern.
  2. Track atoms and energy: Count each type of atom, distinguish coefficients from subscripts, and compare energy before and after the reaction.
  3. Check the evidence: Use observations such as gas, precipitate, temperature, color, or new odor together with conservation and balanced equations.

A coefficient multiplies every atom in the formula and can be changed when balancing an equation.

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