1. Which statement provides the best description of the Law of Conservation of Matter?
- A. The total amount of energy in a system remains constant during a chemical reaction.
- B. Atoms are rearranged to form new substances, but the total mass of the system remains unchanged.
- C. In a chemical reaction, the mass of the products is always significantly greater than the mass of the reactants.
- D. Some atoms are converted into energy during a chemical reaction, causing a decrease in total mass.
2. A chemical reaction starts with 75 grams of reactant A and an unknown mass of reactant B. The reaction produces 110 grams of a single product, C. What was the initial mass of reactant B?
- A. 185 grams
- B. 110 grams
- C. 35 grams
- D. 75 grams
3. A scientist burns 50 grams of wood in a sealed chamber that contains 150 grams of oxygen. After the fire is out, the chamber contains ash and gases. What is the total mass of the ash and gases inside the chamber?
- A. Less than 50 grams
- B. Exactly 150 grams
- C. Exactly 200 grams
- D. More than 200 grams
4. If 12 grams of carbon react completely with 32 grams of oxygen to form carbon dioxide, what will be the total mass of the carbon dioxide produced?
- A. 20 grams
- B. 32 grams
- C. 44 grams
- D. 56 grams
5. According to the Law of Conservation of Matter, what happens to the individual atoms involved in any chemical reaction?
- A. They are changed into new types of atoms.
- B. They are simply rearranged into new combinations.
- C. They are destroyed and cease to exist.
- D. They are converted directly into energy.
6. What is the fundamental principle that requires chemical equations to be balanced?
- A. The principle that reactions must produce energy.
- B. The law of conservation of mass, which states that atoms are not created or destroyed.
- C. The rule that the number of reactant molecules must equal the number of product molecules.
- D. The observation that all chemical reactions are reversible.
7. A chemical reaction starts with 10 atoms of oxygen. If the reaction goes to completion, how many oxygen atoms must be present in the products?
- A. Exactly 10 atoms
- B. Fewer than 10 atoms, because they are consumed in the reaction
- C. More than 10 atoms, as new atoms are formed
- D. Zero, as all the oxygen is converted into energy
8. If a scientist writes a chemical equation that has more atoms on the reactant side than on the product side, what does this unbalanced equation incorrectly imply?
- A. The reaction happened very quickly.
- B. It violates the principle of atom conservation.
- C. The reaction requires a catalyst to finish.
- D. The products are more stable than the reactants were.
9. A reaction involves six carbon atoms as part of the reactants. A student's proposed balanced equation only shows five carbon atoms in the products. Why is this equation incorrect?
- A. It suggests a carbon atom was destroyed.
- B. The reaction must have been incomplete.
- C. It shows that carbon atoms were converted to energy.
- D. The student forgot to include a catalyst.
10. The entire process of balancing chemical equations is a practical application of which major scientific law?
- A. The Law of Thermodynamics
- B. The Law of Universal Gravitation
- C. The Law of Conservation of Mass
- D. The Law of Definite Proportions