What is the chemical formula for rust?

• Fe2O3

• H2O

• CaCO3

• CH4

What does the law of conservation of mass state?

• Matter can be created and destroyed during a chemical reaction.

• Matter is neither created nor destroyed during a chemical reaction.

• Matter is only created during a chemical reaction.

• Matter is only destroyed during a chemical reaction.

Which type of chemical reaction involves two or more elements or compounds combining to form a more complex substance?

• Decomposition reaction

• Replacement reaction

• Synthesis reaction

• Combustion reaction

What are the reactants in the combustion of methane?

• CH4 and O2

• CO2 and H2O

• CaCO3 and O2

• Fe and S

What is the purpose of coefficients in a chemical equation?

• To indicate the type of reaction.

• To balance the equation so the number of atoms in reactants equals the number in products.

• To show the direction of the reaction.

• To represent the subscript numbers in chemical formulas.