Science 7 · Unit 8: Changes to materials · Cambridge Lower Secondary Science Stage 7

Questions

1. 1. Which statement is true?

   • In a physical change, no new substances are formed.
   • When ice melts to form water, it is a chemical change.
   • When you let off fireworks, it is a physical change.
   • When your cells use food to release energy, it is a physical change.
   Check

2. 2. Iron atoms bond with sulfur atoms. What kind of change is this?

   • a chemical change
   • a physical change
   Check

3. 3. Which of these is a physical change?

   • letting off fireworks
   • ice melting to form water
   • iron bonding with sulfur
   • cooking an egg
   Check

4. 4. Which of these is a chemical change?

   • water boiling
   • sugar dissolving
   • ice melting
   • cooking an egg
   Check

5. 5. Your cells use food to release energy. What kind of change is this?

   • a chemical change
   • a physical change
   Check

6. 6. Letting off fireworks is a ... change.

   • chemical
   • physical
   Check

7. 7. Oxygen reacts with hydrogen to form water. What compound is made?

   • oxygen
   • water
   • hydrogen
   • hydrogen peroxide
   Check

8. 8. Which elements make up water?

   • oxygen and nitrogen
   • hydrogen only
   • hydrogen and oxygen
   • hydrogen and carbon
   Check

9. 9. Oxygen reacts with hydrogen to form water. What are the reactants?

   • hydrogen and oxygen
   • water
   • water and oxygen
   • hydrogen and water
   Check

10. 10. Magnesium burns in air. One magnesium atom bonds with one oxygen atom. What is the product?

    • magnesium oxide
    • oxygen magnesium
    • magnesium hydroxide
    • magnesium chloride
    Check

11. 11. An acid is added to a metal and it bubbles. Which gas is given off?

    • hydrogen
    • oxygen
    • carbon dioxide
    • nitrogen
    Check

12. 12. How do you test for hydrogen?

    • It turns limewater milky.
    • A glowing splint relights.
    • It turns universal indicator red.
    • A lighted splint gives a squeaky pop.
    Check

13. 13. Complete the word equation: zinc + hydrochloric acid → zinc chloride + ?

    • hydrogen
    • chlorine
    • water
    • oxygen
    Check

14. 14. Complete the word equation: ? + sulfuric acid → magnesium sulfate + hydrogen

    • magnesium oxide
    • sulfur
    • magnesium
    • zinc
    Check

15. 15. Magnesium reacts with hydrochloric acid. What are the products?

    • magnesium oxide and water
    • magnesium chloride and hydrogen
    • magnesium chloride and oxygen
    • magnesium sulfate and hydrogen
    Check

16. 16. The products of a reaction contain magnesium, hydrogen and chlorine. Which elements are in the reactants?

    • magnesium, hydrogen and chlorine
    • magnesium only
    • hydrogen and chlorine only
    • oxygen and carbon
    Check

17. 📖 This question is about a text that students read in the app.

    17. Look at the results. What volume of hydrogen did 2.0 g of metal give?

    • 120 cm³
    • 220 cm³
    • 150 cm³
    • 260 cm³
    Check

18. 📖 This question is about a text that students read in the app.

    18. What conclusion can Arun and Marcus make from the results?

    • The mass of metal makes no difference.
    • The more metal reacts, the less hydrogen is given off.
    • The more metal reacts, the more hydrogen is given off.
    • Hydrogen is only given off with 5.0 g of metal.
    Check

19. 📖 This question is about a text that students read in the app.

    19. About how much hydrogen does each extra 1 g of metal give?

    • about 50 cm³
    • about 100 cm³
    • about 500 cm³
    • about 10 cm³
    Check

20. 📖 This question is about a text that students read in the app.

    20. If you only had measuring cylinders that hold 100 cm³, what problem would you have?

    • The reading would be too easy.
    • The gas would turn into a liquid.
    • The metal would not react.
    • Most of the gas would not fit, so it could not be measured accurately.
    Check