Chemical Reactions Module Exam Practice Quiz

What is an example of a chemical change showing a change in energy?

• A piece of paper being torn into smaller pieces.

• A metal rod becoming warm after being left in the sun.

• A glow stick glowing after being bent and shaken.

• Salt dissolving in water.

Answer explanation

A glow stick glowing after being bent and shaken is a chemical change that releases energy in the form of light. This process involves a chemical reaction, demonstrating a clear change in energy.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS1-5

What is an example of a chemical change that forms a precipitate?

• Mixing vinegar and baking soda to produce bubbles.

• Mixing silver nitrate and sodium chloride to form a white solid.

• Heating water to produce steam.

• Dissolving sugar in water to make a solution.

Answer explanation

Mixing silver nitrate and sodium chloride results in a chemical change where a white solid precipitate (silver chloride) forms, indicating a reaction has occurred. The other options do not produce a precipitate.

Tags

NGSS.MS-PS1-2

What is the sign of a chemical reaction in this image?

• A gas being produced

• A solid dissolving in a liquid

• A liquid evaporating

• A color change

Answer explanation

The correct choice is 'A gas being produced' because it indicates a chemical reaction has occurred, often evidenced by bubbles or fizzing, which signifies gas release.

In the chemical reaction represented in the image, what is represented by C and D?

• Reactants

• Products

• Formations

• Precipitates

Answer explanation

In a chemical reaction, C and D represent the products formed after the reactants undergo a transformation. Therefore, the correct choice is 'Products'.

Tags

NGSS.HS-PS1-7

Which of the following is an example of a chemical formula?

• Water

• CH₄ + 2O₂ → CO₂ + 2H₂O

• HCl + NaOH → NaCl + H₂Owaterwat

• H₂O

Answer explanation

The correct choice is H₂O, which is a simple chemical formula representing water. Other options include chemical reactions or are incorrectly formatted, making H₂O the only valid example of a chemical formula.

What is the correct chemical equation for this word equation?

Iron metal reacts with oxygen gas to produce iron(III) oxide

• Fe(s) + O₂(g) → Fe₂O₃(s)

• 2Fe(s) + 3O₂(g) → 2Fe₂O₃(s)

• 4Fe(s) + 3O₂(g) → 2Fe₂O₃(s)

• 3Fe(s) + O₂(g) → Fe₃O₄(s)

Answer explanation

The correct equation is 4Fe(s) + 3O₂(g) → 2Fe₂O₃(s) because it balances the number of iron and oxygen atoms, producing iron(III) oxide from iron and oxygen.

Tags

NGSS.HS-PS1-7

What word equation best describes the following chemical equation?
CaCO₃(s) → CaO(s) + CO₂(g)

• Calcium carbonate reacts with oxygen to produce calcium and carbon dioxide

• Calcium carbonate decomposes to produce calcium oxide and carbon dioxide

• Calcium reacts with carbon dioxide to produce calcium carbonate

• Calcium oxide reacts with carbon dioxide to produce calcium carbonate

Answer explanation

The correct choice is that calcium carbonate decomposes to produce calcium oxide and carbon dioxide, as indicated by the reaction where CaCO₃ breaks down into CaO and CO₂.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of the following is a coefficient in this equation?
2H₂(g) + O₂(g) → 2H₂O(l)

• 2

• H₂

• O₂

• H₂O

Answer explanation

In the equation 2H₂ + O₂ → 2H₂O, the number '2' before H₂ and H₂O are coefficients, indicating the number of molecules. Therefore, '2' is the correct answer as it represents the quantity of H₂ and H₂O in the reaction.

Which of the following examples best describes the Law of Conservation of Mass?

• In a chemical reaction, the mass of the products is greater than the mass of the reactants

• A chemical reaction occurs in a closed container, and the total mass of the products equals the total mass of the reactants

• When a gas is produced in a chemical reaction, the mass of the products is less than the mass of the reactants

• In a combustion reaction, the mass of oxygen used is greater than the mass of the other reactants

Answer explanation

The Law of Conservation of Mass states that in a closed system, the total mass remains constant. The correct choice illustrates this principle, showing that the mass of products equals the mass of reactants.

Tags

NGSS.HS-PS1-7

What is the total number of hydrogen atoms (H) represented by the coefficient and formula 3C₆H₁₂O₆?

• 3

• 12

• 36

• 72

Answer explanation

The formula 3C₆H₁₂O₆ indicates 3 molecules of glucose. Each glucose has 12 hydrogen atoms (H). Therefore, 3 x 12 = 36 hydrogen atoms in total, making the correct answer 36.

Tags

NGSS.MS-PS1-1