Chemical Changes

Multiple Choice

Which of the following best describes a chemical reaction?

• A process where substances change to form new substances

• A process where substances mix but do not change

• A process where substances are separated physically

• A process where substances are cooled down

Fill in the Blanks

The arrow (→) in a chemical equation is read as "

."

Multiple Choice

Which of the following best describes what happens to reactants during a chemical reaction?

• They are broken down and new bonds form to create products.

• They remain unchanged throughout the reaction.

• They are always gases.

• They disappear without forming anything new.

Multiple Select

Which of the following symbols are correctly matched with their meanings in chemical reactions?

• (s) = solid

• (aq) = aqueous solution

• (g) = gas

• (l) = light

Multiple Choice

Which observation would best indicate the formation of a gas during a chemical reaction?

• Bubbling or the appearance of an odor (other than boiling)

• A decrease in temperature

• A color change

• The formation of a solid

Multiple Choice

What does a color change in a substance during a reaction usually indicate?

• A new substance has formed

• The temperature has increased

• The substance has melted

• The reaction has stopped

Multiple Choice

Which of the following is evidence that a chemical reaction has occurred, as shown in the image?

• Formation of a precipitate

• Increase in temperature

• Change in color only

• Production of a gas

Fill in the Blanks

During a chemical reaction, atoms are neither created nor destroyed. This is known as the law of

of mass.

Multiple Select

Which of the following properties are conserved during a chemical reaction?

• Mass

• Types of atoms

• Color

• Number of each atom

Multiple Choice

Which of the following is NOT one of the five basic types of chemical reactions listed?

• Single Replacement

• Double Replacement

• Neutralization

• Combustion

Multiple Choice

In a single replacement reaction, what happens to the elements involved?

• A single element replaces another in a compound

• Two compounds exchange elements

• Two elements combine to form a compound

• A compound breaks down into elements

Multiple Choice

Which type of reaction involves two aqueous ionic compounds switching places to form two new compounds?

• Double replacement reaction

• Synthesis reaction

• Decomposition reaction

• Combustion reaction

Multiple Choice

Given the reaction: 2Mg + O2 → 2MgO, identify the reactants and the product.

• Reactants: 2Mg, O2; Product: 2MgO

• Reactants: 2MgO; Product: 2Mg, O2

• Reactants: O2, 2MgO; Product: 2Mg

• Reactants: 2Mg, 2MgO; Product: O2

Multiple Select

Which of the following are always true about combustion reactions?

• They are exothermic

• They always produce carbon dioxide and water

• They require oxygen

• They always produce a blue flame