Combustion and Flame

Grade 7 Science — Combustion and Flame: 25 practice questions with instant scoring and explanations.

1. Combustion requires three elements, known as the
2. The three elements necessary for combustion are
3. Ignition temperature is the
4. Which type of combustion produces light and heat suddenly?
5. Spontaneous combustion occurs when
6. Slow combustion is exemplified by
7. A flame has three distinct zones: outer, middle, and
8. The hottest zone of a flame is the
9. The innermost zone of a flame is
10. The color of flame depends on
11. Calorific value of a fuel is measured in
12. Which fuel has the highest calorific value?
13. Complete combustion produces
14. Incomplete combustion produces
15. Carbon monoxide is a
16. The blue color of a gas flame indicates
17. Fire extinguishers work by removing
18. Water is effective in extinguishing fires because it
19. Class C fires involve
20. Burning magnesium produces a
21. The smoke from a candle comes from
22. Fuel efficiency is the ratio of
23. Which fuel produces the least pollution?
24. The zone of a flame that has the brightest light is
25. When combustion is complete, the products are primarily