What does the law of conservation of mass state about matter during a chemical reaction?

• Matter is created and destroyed.

• Matter is only changing, not created or destroyed.

• Matter disappears completely.

• Matter turns into energy.

Which of the following is an example of a chemical reaction described in the text?

• Melting ice

• Mixing sand and water

• Burning wood in a campfire

• Dissolving sugar in tea

What do scientists use to describe what happens in a chemical reaction?

• Pictures

• Equations

• Stories

• Poems

How are chemical symbols for elements represented in the periodic table?

• By numbers only

• By colors

• By a capital letter or a capital letter and a lowercase letter

• By shapes

A teacher mixes hydrogen peroxide, yeast, and liquid soap to create "elephant toothpaste." Based on the information provided, which two elements are involved in the reaction?

• Hydrogen and carbon

• Oxygen and nitrogen

• Hydrogen and oxygen

• Carbon and nitrogen

What does a chemical equation use to describe what happens in a chemical reaction?

• Pictures and diagrams

• Words and sentences

• Chemical symbols and numbers

• Physical models

In a chemical equation, what does the arrow between the reactants and products represent?

• The start of the reaction

• The end of the reaction

• "Yields" or produces

• The temperature of the reaction

Which of the following best describes the role of coefficients in a chemical equation?

• They tell the number of atoms in a molecule

• They tell the number of units needed or produced from a reaction

• They show the temperature at which the reaction occurs

• They indicate the color of the substances

If you are given the chemical equation 4Fe + 3O₂ → 2Fe₂O₃, how many atoms of iron are present on the reactant side?

• 2

• 3

• 4

• 6

Why is it important to use the periodic table when writing chemical equations?

• To find the melting points of elements

• To identify the correct symbols for elements involved in the reaction

• To determine the color of the elements

• To measure the mass of the elements