Exothermic and Endothermic Reactions Quiz

1. Which of the following is a defining characteristic of an exothermic reaction?

• A. Energy is transferred to the surroundings and the temperature rises
• B. Energy is taken from the surroundings and the temperature falls
• C. The reaction requires activation energy to proceed
• D. The products have more energy stored than the reactants

2. Which of the following is an example of an endothermic reaction?

• A. Combustion of natural gas
• B. Neutralisation of hydrochloric acid with sodium hydroxide
• C. Thermal decomposition of calcium carbonate
• D. Oxidation of magnesium in oxygen

3. What is meant by activation energy in the context of chemical reactions?

• A. The total amount of energy released or absorbed during the reaction
• B. The minimum energy required for a reaction to occur
• C. The energy stored in the chemical bonds of the products
• D. The energy lost to the surroundings as heat

4. A student carries out the reaction between citric acid and sodium hydrogen carbonate in a polystyrene cup and measures the temperature change. The temperature drops by 8 °C. What can the student conclude?

• A. The reaction is exothermic because the temperature decreased
• B. The reaction is endothermic because energy is taken from the surroundings
• C. The reaction must require a very high activation energy
• D. The products contain less chemical energy than the reactants

5. In an energy level diagram for an exothermic reaction, which of the following statements is correct?

• A. The products are at a higher energy level than the reactants, and ΔH is positive
• B. The reactants are at a higher energy level than the products, and ΔH is negative
• C. The activation energy is greater than the energy released to the surroundings
• D. The energy level of the products determines the activation energy of the reaction