Science 6 · Unit 2: Materials: properties and changes · Cambridge Primary Science Stage 6

Questions

1. 1. What is a chemical reaction?

   • when salt dissolves
   • when substances react together to form new substances
   • when ice melts
   • when water evaporates
   Check

2. 2. What are reactants?

   • the container
   • the new substances formed
   • the substances that react together
   • the heat
   Check

3. 3. What are products?

   • the equipment used
   • the new substances that form
   • the substances at the start
   • the bubbles only
   Check

4. 4. In vinegar + bicarbonate of soda, what are the reactants?

   • the jar and spoon
   • only vinegar
   • vinegar and bicarbonate of soda
   • carbon dioxide and water
   Check

5. 5. What gas is produced when vinegar reacts with bicarbonate of soda?

   • hydrogen sulfide
   • oxygen
   • carbon dioxide
   • nitrogen
   Check

6. 6. What happens when you breathe out through a straw into limewater?

   • It boils.
   • It freezes.
   • It turns cloudy.
   • It turns blue.
   Check

7. 7. What product forms when limewater reacts with carbon dioxide?

   • oxygen
   • sugar
   • calcium carbonate
   • salt
   Check

8. 8. Wire wool in vinegar gets warmer over five minutes. What does this show?

   • The thermometer is broken.
   • The vinegar is boiling.
   • Nothing happens.
   • A chemical reaction is taking place.
   Check

9. 9. Which is evidence of a chemical reaction?

   • a colour change from clear to yellow
   • sugar dissolving
   • liquid droplets forming above a solution
   • ice melting
   Check

10. 10. Which is not evidence of a chemical reaction?

    • liquid droplets forming above a solution
    • a bad-smelling gas
    • bubbles of a new gas
    • a change in temperature
    Check

11. 11. Iron and sulfur are heated to form iron sulfide. What is the product?

    • heat
    • sulfur
    • iron sulfide
    • iron
    Check

12. 12. Cooking gas burns in oxygen to form carbon dioxide and water. Which is a reactant?

    • oxygen
    • water
    • carbon dioxide
    • heat
    Check

13. 13. Magnesium burns with a bright white flame to form a white powder. Which is the product?

    • the flame
    • magnesium
    • oxygen
    • the white powder
    Check

14. 14. Why is an egg rotting a chemical reaction?

    • The yolk separates.
    • A bad-smelling gas is formed.
    • The egg shrinks.
    • The egg gets colder.
    Check

15. 15. An iron nail rusts in water. What evidence of a reaction is there?

    • the water boils
    • a new orange-brown substance (rust) forms
    • the nail becomes magnetic
    • the nail floats
    Check

16. 16. Plants use carbon dioxide and water to make glucose and oxygen. What are the products?

    • only water
    • glucose and oxygen
    • sunlight and soil
    • carbon dioxide and water
    Check

17. 17. Zara drops a fizzy tablet into water. What evidence of a reaction will she see?

    • nothing
    • the water turning solid
    • ice forming
    • bubbles of gas
    Check