Science 9 · Unit 8: Rates of reaction · Cambridge Lower Secondary Science Stage 9

Questions

1. 1. Magnesium powder burns much faster than a block of magnesium of the same mass. Why?

   • More of its atoms are on the surface, in contact with oxygen.
   • The powder is made of a different metal.
   • The powder is heavier.
   • The block contains more oxygen.
   Check

2. 2. An iron nail, some iron wool and some iron filings are each held in a Bunsen flame. Which reacts fastest?

   • the iron nail
   • the iron filings
   • They all react at the same rate.
   • the iron wool
   Check

3. 3. 27 cubes, all the same size, are arranged to form one large cube (3 by 3 by 3). How many faces of small cubes make up one face of the large cube?

   • 6
   • 9
   • 27
   • 3
   Check

4. 4. 27 cubes form one large cube (3 by 3 by 3). How many faces of small cubes make up the whole outside of the large cube?

   • 54
   • 27
   • 9
   • 162
   Check

5. 5. The 27 cubes are separated from one another. How many faces of small cubes are on the outside now?

   • 27
   • 162
   • 81
   • 54
   Check

6. 6. 27 small cubes are arranged as one big cube, then as a flat slab, then all separated. Which has the largest total surface area?

   • the flat slab
   • all the cubes separated
   • the one big cube
   • they are all the same
   Check

7. 7. Small calcium carbonate chips and large chips of the same total mass are each added to the same volume of hydrochloric acid. Which reaction will be fastest?

   • the one with the large chips
   • They will both go at the same rate.
   • the one with the small chips
   • Neither will react.
   Check

8. 8. Zara reacts zinc with hydrochloric acid and collects the gas over water. Which gas?

   • oxygen
   • carbon dioxide
   • hydrogen
   • chlorine
   Check

9. 9. What is the word equation for zinc + hydrochloric acid?

   • zinc + hydrochloric acid → zinc chloride + hydrogen
   • zinc + hydrochloric acid → zinc sulfate + hydrogen
   • zinc + hydrochloric acid → zinc oxide + water
   • zinc + hydrochloric acid → zinc chloride + water
   Check

10. 10. Which is a practical problem with collecting gas over water in a measuring cylinder?

    • The gas changes colour.
    • Some gas may escape before the bung is put in.
    • The zinc dissolves in the water.
    • The measuring cylinder melts.
    Check

11. 11. Zara compares a flat piece and a lump of zinc of the same mass. How does the total volume of gas compare at the end?

    • the same
    • higher with the lump
    • lower with the lump
    Check

12. 12. Which reacts faster, the flat piece or the lump of zinc?

    • the flat piece
    • the lump
    Check

13. 13. Describe the graph for the flat piece of zinc.

    • It stays flat the whole time.
    • It rises at a steady rate until 400 s.
    • It rises slowly at first, then very quickly at the end.
    • It rises steeply at first, then more slowly, and levels off at 40 cm³ after about 270 s.
    Check

14. 14. How is the line for the lump of zinc different from the flat piece?

    • It is exactly the same.
    • It ends at a lower volume.
    • It is steeper and ends higher.
    • It is less steep, and takes longer to reach 40 cm³.
    Check

15. 15. Use collision theory. Why does the flat piece react faster than the lump?

    • It has a larger surface area, so there are more collisions with acid particles each second.
    • It has more zinc atoms.
    • It is hotter.
    • The acid is stronger.
    Check

16. 16. How would the line for the same mass of powdered zinc look?

    • steeper, ending at a much higher volume
    • steeper at the start, levelling off sooner at the same final volume
    • the same as the lump
    • less steep, ending higher
    Check