7.2.3 Quiz

Which takes place when a chemical change occurs? Choose the letter of the best answer.

• Bonds connecting atoms in products and reactants form.

• Bonds connecting atoms in products and reactants break.

• Bonds connecting atoms in reactants break, and bonds connecting atoms in products form.

• Bonds connecting atoms in reactants form, and bonds connecting atoms in products break.

In photosynthesis, water (H₂O) and carbon dioxide (CO₂) react to form oxygen (O₂) and glucose (C₆H₁₂O₆). The following table shows the reactants and products of photosynthesis. What number should replace the question mark to show the number of C₆H₁₂O₆ (glucose) molecules in a balanced chemical equation?

• 1

• 2

• 6

• 12

Which of the following is an example of an endothermic reaction? Choose the letter of the best answer.

• a cake baking

• a candle burning

• fireworks exploding

• a piece of wood smoldering

Why does increasing temperature generally increase the rate of a chemical reaction? Choose the letter of the best answer.

• It increases the amount of reactant.

• It decreases the size of the reactant particles.

• It causes the particles of the reactants to move faster and collide more often.

• It increases the space between reactant particles so they have more room to move apart.

When coal is burned, sulfur is released into the air, where it reacts with oxygen to produce sulfur dioxide and sulfur trioxide. Which of the following is true of this process? Choose the letter of the best answer.

• The identity of each reactant remains the same.

• Sulfur dioxide and sulfur trioxide are the reactants in this change.

• The products have different chemical properties from those of the reactants.

• The products contain more sulfur atoms and fewer oxygen atoms than the reactants.