Secondary 2 Science Normal Academic Topic: Chemical Changes Test Duration: 1 Hour Total Marks: 50
Part A: Multiple Choice Questions (1 mark each) Circle the correct answer.
- What is a sign that a chemical change has occurred?
- A) Change in shape
- B) Change in state
- C) Formation of a precipitate
- D) Change in mass
- Which of the following is an example of a chemical change?
- A) Boiling water
- B) Melting ice
- C) Burning paper
- D) Dissolving salt in water
- What type of reaction involves heat energy being released into the surroundings?
- A) Endothermic reaction
- B) Exothermic reaction
- C) Reversible reaction
- D) Physical change
- Which gas is commonly produced when an acid reacts with a metal?
- A) Oxygen
- B) Hydrogen
- C) Carbon dioxide
- D) Nitrogen
- In a chemical reaction, the substances that are used up are called:
- A) Products
- B) Reactants
- C) Catalysts
- D) Indicators
Part B: Short Answer Questions (5 marks each) Answer the following questions briefly.
- Explain why rusting of iron is considered a chemical change.
- Describe what happens during a displacement reaction and give an example using copper sulfate and zinc.
- List three indicators that can be used to tell if a chemical reaction has taken place.
- What is meant by conservation of mass in chemical reactions? Provide an example to illustrate this principle.
- Define oxidation and reduction in terms of electron transfer, and provide an example for each.
Part C: Structured Questions (10 marks each) Provide detailed answers to the questions below.
- A student mixed 25 mL of sodium hydroxide solution with 25 mL of hydrochloric acid and noticed a temperature increase. Explain why this temperature change occurred, including the type of reaction and why it is important to the reaction process.
- Design an experiment to investigate the effect of concentration on the rate of a chemical reaction. Include the objective, materials, procedure, variables, and how you would present your results.