Science 7 · Unit 2: Materials and their structure · Cambridge Lower Secondary Science Stage 7

Questions

1. 1. What happens in a mixture?

   • One substance changes into a different element.
   • A single kind of atom is split up.
   • Two or more elements bond together to make a new substance.
   • Two or more substances are mixed, but no new substance is made.
   Check

2. 2. Sofia heats iron filings and sulfur powder together. What does she produce?

   • a mixture of iron and sulfur
   • a new compound, iron sulfide
   • pure iron
   • iron sulfate
   Check

3. 3. Marcus mixes iron filings and sulfur in a beaker and stirs until they are completely mixed. Does he produce a new product?

   • Yes, he makes a new element.
   • Yes, he makes iron sulfide.
   • No, the sulfur disappears.
   • No, he makes a mixture.
   Check

4. 4. Marcus holds a magnet over his beaker of iron and sulfur. What happens?

   • Everything in the beaker is attracted to the magnet.
   • The iron filings are attracted to the magnet.
   • The sulfur is attracted to the magnet.
   • Nothing is attracted, because iron sulfide is not magnetic.
   Check

5. 5. At the end of Sofia's experiment, she holds a magnet near the test tube. What happens?

   • The sulfur is pulled out of the iron sulfide.
   • All of the iron sulfide jumps to the magnet.
   • The iron is pulled out of the iron sulfide.
   • Nothing is attracted, because iron sulfide is not magnetic.
   Check

6. 6. True or false: At the end of Marcus's experiment, the beaker contains a compound.

   • True
   • False
   Check

7. 7. True or false: compounds have the same properties as the elements they are made from.

   • True
   • False
   Check

8. 8. Look at the particle diagrams. Which boxes contain gases?

   • B, E and F
   • A and D only
   • C and F
   • A, C and D
   Check

9. 9. Look at the particle diagrams. Which boxes contain a mixture?

   • A, B and D
   • C and E
   • A and C only
   • E and F
   Check

10. 10. Look at the particle diagrams. Which box contains a liquid?

    • F
    • E
    • B
    • D
    Check

11. 11. Look at the particle diagrams. Which box contains a mixture of elements that is a solid?

    • D
    • B
    • C
    • E
    Check

12. 12. Look at the particle diagrams. Which box contains a mixture of compounds?

    • F
    • A
    • C
    • E
    Check

13. 13. What is the main difference between a compound of two elements and a mixture of the same two elements?

    • The compound has more atoms than the mixture.
    • The mixture is always a liquid and the compound is always a solid.
    • There is no difference.
    • In the compound the atoms are bonded together; in the mixture they are not.
    Check

14. 14. How are the properties of a mixture of iron and sulfur different from those of iron sulfide?

    • The compound keeps the properties of iron and sulfur; the mixture has new properties.
    • Neither has any of the properties of iron or sulfur.
    • They have exactly the same properties.
    • The mixture keeps the properties of iron and sulfur; the compound has new properties.
    Check

15. 15. Which is the easiest to separate back into iron and sulfur?

    • the compound, by stirring
    • the compound, using a magnet
    • neither can be separated
    • the mixture, using a magnet
    Check

16. 16. Which of these is a mixture?

    • carbon dioxide
    • oxygen
    • air
    • water
    Check

17. 17. Which gas makes up about 78% of the air?

    • carbon dioxide
    • water vapour
    • oxygen
    • nitrogen
    Check

18. 18. Why does the amount of water vapour in air keep changing?

    • Plants make water vapour only at night.
    • Air is a compound, so it changes all the time.
    • It depends on the weather.
    • Nitrogen turns into water vapour.
    Check

19. 19. What does 'pure' mean in science?

    • It has been boiled.
    • It is clean and safe to drink.
    • It contains only one substance.
    • It is a mixture of natural substances.
    Check

20. 20. Some tap water is boiled in an evaporating basin until all the water has gone. A white solid is left. What does this show?

    • The tap water was a mixture of water and dissolved substances.
    • The tap water was pure water.
    • The evaporating basin melted.
    • The heat made a new element.
    Check