🧪 Part 1: Multiple Choice

1. Which of the following is evidence that a chemical reaction has occurred?

Change in temperature

Production of gas bubbles

Change in colour

All of the above

2. What type of reaction is represented by: A + B → AB?

Decomposition

Synthesis (combination)

Single displacement

Double displacement

3. In the equation 2H₂ + O₂ → 2H₂O, the coefficient 2 in front of H₂O represents:

2 atoms of water

2 molecules of water

2 elements in water

2 grams of water

4. Which of the following are signs you might observe during a chemical reaction? (Select all that apply)

Formation of a precipitate

Release of energy (heat or light)

Change in state only

Production of new odours

⚖️ Part 2: Balancing Equations

5. Balance the following chemical equations by filling in the coefficients:

a) _____ Mg + _____ O₂ → _____ MgO

b) _____ Na + _____ Cl₂ → _____ NaCl

c) _____ CaCO₃ → _____ CaO + _____ CO₂

6. Classify each of the reactions in Question 5 as synthesis, decomposition, single displacement, or double displacement:

✏️ Part 3: Short Answer Questions

7. Explain the difference between a physical change and a chemical change. Give one example of each.

8. You mix baking soda (sodium bicarbonate) with vinegar (acetic acid) and observe fizzing and bubbling. Explain what is happening and why this indicates a chemical reaction has occurred.

9. Why is it important to balance chemical equations? What law does this relate to?

10. Design a simple experiment you could do at home to demonstrate a chemical reaction. List the materials needed and describe what you would observe.