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

Questions

1. 1. In the picture, Marcus is heating water in a beaker over a Bunsen burner. Which safety precaution is he taking?

   • holding the beaker in his hand
   • heating the water as fast as possible
   • leaning over the beaker to look in
   • wearing safety goggles
   Check

2. 2. Why does Marcus measure the temperature at 0 minutes, before he starts heating?

   • because the water is boiling then
   • to make the water heat faster
   • to check the thermometer is hot
   • to know the starting temperature, so he can see how much it rises
   Check

3. 3. Marcus measures the temperature of water every minute as he heats it. Which headings should his results table have?

   • Time in minutes | Temperature in °C
   • Beaker | Water
   • Minutes in °C | Heat
   • Time | Temperature
   Check

4. 4. The diagram shows Marcus's thermometer after 2 minutes. What temperature does it show?

   • 40 °C
   • 38 °C
   • 36 °C
   • 48 °C
   Check

5. 5. The diagram shows Marcus's thermometer after 5 minutes. What temperature does it show?

   • 60 °C
   • 62 °C
   • 52 °C
   • 64 °C
   Check

6. 6. Marcus plots his results on a graph. Where should time go?

   • in the title
   • along the horizontal axis
   • up the vertical axis
   • on both axes
   Check

7. 7. Marcus's points lie on a straight line. What does this show?

   • The temperature went down every minute.
   • The temperature rose by about the same amount every minute.
   • The water was boiling all the time.
   • The temperature stayed the same.
   Check

8. 8. Zara's results: 0 min 22 °C, 1 min 29 °C, 2 min 38 °C, 3 min 48 °C, 4 min 59 °C, 5 min 61 °C, 6 min 78 °C, 7 min 85 °C, 8 min 92 °C, 9 min 93 °C, 10 min 92 °C. Which result does not fit the pattern?

   • 9 minutes, 93 °C
   • 10 minutes, 92 °C
   • 4 minutes, 59 °C
   • 5 minutes, 61 °C
   Check

9. 9. Zara has one result that does not fit the pattern on her graph. What should she do?

   • throw away all her results
   • change the number so it fits the line
   • draw her line through that point anyway
   • ignore it when she draws her line
   Check

10. 10. How should Zara draw a line of best fit through points that follow a curve?

    • a curve that goes through every point, including the odd one
    • straight lines joining each point to the next, dot to dot
    • a straight line from the first point to the last point
    • a smooth curve with about the same number of points above and below it
    Check

11. 11. Zara's points follow a curve that rises steeply, then flattens out. What does her graph show?

    • The temperature rose by the same amount every minute.
    • The temperature rose quickly at first, then stopped rising when the liquid boiled.
    • The temperature fell, then rose.
    • The liquid froze at the end.
    Check

12. 12. What happens to the temperature of Zara's liquid as she keeps heating it?

    • It stays the same the whole time.
    • It falls back to room temperature.
    • It keeps rising by the same amount every minute.
    • It rises quickly at first, then stops rising and stays about the same.
    Check

13. 13. Zara measures the volume of the water before and after heating it to boiling for a few minutes. What will she find?

    • There is no water left at all.
    • There is less water at the end, because some turned into steam and escaped.
    • The volume is exactly the same.
    • There is more water at the end, because it expanded.
    Check

14. 14. What is the melting point of a substance?

    • the highest temperature a solid can reach
    • the temperature at which a liquid changes to a gas
    • the temperature at which a liquid freezes into a gas
    • the temperature at which it changes from a solid to a liquid
    Check

15. 15. Match each change of state to its name.

    • solid to liquid
    • liquid to solid
    • liquid to gas
    • gas to liquid

    • freezing
    • evaporating
    • condensing
    • melting
    Check

16. 16. A puddle dries up on a warm day, even though the water never gets to 100 °C. What is this change called?

    • condensation
    • boiling
    • melting
    • evaporation
    Check