Unit 2 Review 2024

In the chemical reaction CH₄ + 2O₂ → CO₂ + 2H₂O, what are the reactants?

• CH₄ and O₂

• CO₂ and H₂O

• CH₄ and H₂O

• CO₂ and O₂

How many molecules of oxygen (O₂) are required in the reaction CH₄ + 2O₂ → CO₂ + 2H₂O?

• 1

• 2

• 3

• 4

What does the Law of Conservation of Mass state?

• Matter is created during a chemical reaction.

• Matter is destroyed during a chemical reaction.

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

• Matter is both created and destroyed during a chemical reaction.

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

• The total mass of reactants is always less than the total mass of products.

• The total mass of reactants is always more than the total mass of products.

• The total mass of reactants is equal to the total mass of products.

• The total mass of reactants and products cannot be compared.

What is the left part of a chemical equation called?
H_{2 +} O → H₂O

• Reactants
• Products 
• Yields 
• Chemical Equation 

A shorter, easier way to show a chemical reaction, using symbols instead of words, is called a..............

• chemical formula

• symbol

• chemical equation

• subscript

Which of the following models best demonstrates a balanced chemical equation?

• F
• G
• H
• J

How many atoms in all are in a molecule of serotonin?

C₁₀H₁₂N₂O

• 22
• 24
• 25
• 4

Coal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the best evidence that a chemical reaction occurs when coal burns?

• The shape of the coal changes
• Oxygen is present
• A new substance is produced
• Coal is made up of more than one element

Which of the following equations demonstrates an actual chemical reaction that forms a new substance? (HINT: it must follow the Law of Conservation of Mass)

• A
• B
• C
• D