Quick answer: Combustion is a fast reaction of a fuel with oxygen that releases heat and light. This grade 8 science test on combustion has 8 questions worth 20 marks, to do in 45 minutes: fire triangle, limewater apparatus and balance ethane burning. The mark scheme is on a separate page; free printable PDF.
Also, this test covers the fire triangle, combustion equations, the limewater test, carbon monoxide and mass calculations. Show all working and write balanced equations clearly. In addition, you have 45 minutes and the test is worth 20 marks.
Level: Grade 8 science (Year 9 · Class 8) · Curriculum: MS-PS1-2
Question 1 Fire triangle (2 marks)
Name the three parts of the fire triangle and state what happens if you remove one.Question 2 Limewater apparatus (3 marks)
The gases from burning methane pass through limewater as shown.- Firstly, state what you would see in the limewater. (1 mark)
- Name the gas that causes it and the white solid formed. (1 mark)
- Then write the word equation for this reaction. (1 mark)
Question 3 Balance ethane burning (3 marks)
When ethane burns completely, the reaction is: C₂H₆ + O₂ → CO₂ + H₂O.- Firstly, balance the equation with whole numbers. (2 marks)
- Then show that each element balances. (1 mark)
Question 4 Carbon monoxide (3 marks)
Explain why carbon monoxide is dangerous, how it forms and how you can reduce its risk.Question 5 Mass of carbon dioxide (3 marks)
6.0 g of carbon burns with 16.0 g of oxygen and produces 22.0 g of carbon dioxide.- Show that mass is conserved. (1 mark)
- Calculate the mass of CO₂ produced from 9.0 g of carbon. (1 mark)
- Calculate the mass of oxygen needed for 9.0 g of carbon. (1 mark)
Question 6 Complete or incomplete (2 marks)
State two differences between complete and incomplete combustion of methane.Question 7 Candle under a jar (2 marks)
A candle goes out after a short time when it burns under a closed jar. Explain this using the fire triangle.Question 8 Fire at the office (2 marks)
Then suggest which extinguisher to use on an electrical fire, water or carbon dioxide, and explain why.
