Science 8 · Unit 8: Chemical reactions · Cambridge Lower Secondary Science Stage 8

Questions

1. 1. What is the general word equation for a metal and an acid?

   • metal + acid → hydroxide + oxygen
   • metal + acid → salt + hydrogen
   • metal + acid → oxide + water
   • metal + acid → carbon dioxide
   Check

2. 2. How can you tell a reaction between a metal and acid is happening?

   • nothing changes
   • the acid freezes
   • bubbles of gas are given off
   • the metal turns to gold
   Check

3. 3. How can you tell which metal is more reactive?

   • It is heavier.
   • It is shinier.
   • It produces bubbles more quickly.
   • It produces no bubbles.
   Check

4. 4. Sofia and Zara used nitric acid for one metal and hydrochloric acid for the others. Why is it not fair?

   • They used test tubes.
   • Nitric acid is not an acid.
   • The type of acid was not kept the same.
   • They used too much metal.
   Check

5. 5. Marcus used dilute acid and Arun used very dilute acid. Why can't they compare results?

   • They tested on different days.
   • They used different coloured tubes.
   • The acid concentration was different.
   • Their metals were too shiny.
   Check

6. 6. In a fair test of metals with acid, what should be kept the same?

   • only the test tube
   • the acid type, concentration and volume, and the size of metal
   • nothing
   • the type of metal
   Check

7. 7. Look at Zara's results. Which metal was the most reactive?

   • lead
   • aluminium
   • magnesium
   • iron
   Check

8. 8. Look at Zara's results. Which metal was the least reactive of those that reacted?

   • lead
   • zinc
   • aluminium
   • magnesium
   Check

9. 9. Zara also tested copper, but there is no result for it in the table. Why?

   • Copper exploded.
   • Copper does not react with dilute hydrochloric acid.
   • Zara forgot.
   • Copper is magnetic.
   Check

10. 10. Look at Zara's results. Zinc took 54 s, but it should be only a little less reactive than aluminium (27 s). What might explain this?

    • The timer was perfect.
    • Zinc is not a metal.
    • Hydrogen doesn't come from zinc.
    • The zinc piece was a different size or had an oxide coating.
    Check

11. 11. Why is it hard to get accurate results with this method?

    • The reaction never starts.
    • Acids are colourless.
    • It is difficult to judge exactly when the tube is full and to start timing.
    • Hydrogen is visible.
    Check

12. 12. How could Zara improve accuracy?

    • guess the times
    • repeat each test and use a gas syringe to measure volume
    • use different acids
    • do each test once
    Check

13. 13. What salt forms when zinc reacts with hydrochloric acid?

    • zinc oxide
    • zinc sulfate
    • zinc nitrate
    • zinc chloride
    Check

14. 14. What salt forms when magnesium reacts with sulfuric acid?

    • magnesium chloride
    • magnesium nitrate
    • magnesium sulfate
    • magnesium oxide
    Check

15. 15. How should you stay safe when using acids?

    • taste the acid
    • use bare hands
    • wear safety glasses
    • work without a teacher
    Check

16. 16. What is the word equation for zinc and nitric acid?

    • zinc + nitric acid → zinc oxide + water
    • zinc + nitric acid → zinc nitrate + hydrogen
    • zinc + nitric acid → zinc + nitrogen
    • zinc + nitric acid → zinc chloride + hydrogen
    Check

17. 17. Which metals should not be used when testing reactivity with dilute acid in school?

    • sodium and potassium
    • magnesium and zinc
    • zinc and iron
    • copper and iron
    Check