N.Sc

4. a chemical reaction that happens when objects or substances are burned.
5. a chemical reaction that happens in some living things, such as yeast and bacteria
9. current the flow of electrical charges through materials.
12. a type of matter which contains two or more pure substances.
13. circuit a closed path through which electricity flows.
14. a material which does not allow electrical charges to move.
16. a method used to separate substances of different density in heterogeneous
17. a material which allows electrical charges to move.
20. mixture :a mixture in which the different components can be distinguished.
22. a chemical reaction that happens when some metal substances such as iron combine with oxygen in the presence of water
23. mixture :a mixture in which the different components cannot be distinguished.

1. an object which can attract other objects made of iron and other magnetic metals.
2. reactions these happen when atoms react and group together differently.
3. a device with a magnetic needle that always points north. We use it to orient ourselves.
6. a method used to separate solids from liquids in homogeneous mixtures.
7. a method used to separate solids from liquids, or solids with different size particles, in heterogeneous mixtures.
8. another word for a homogeneous mixture.
10. the force of attraction exerted by magnets.
11. substance a type of matter which contains only one type of component.
15. a connecting wire, usually made of copper, wrapped in plastic covering.
18. a method used to separate liquids that have different boiling points in homogeneous mixtures
19. the component of an electric circuit which provides the electricity.
21. the component of an electric circuit which transforms electricity into another type of energy.