Science 8 · Unit 2: Properties of materials · Cambridge Lower Secondary Science Stage 8

Questions

1. 1. Sofia predicted 'If we use more water, more salt will dissolve.' What was the independent variable?

   • the temperature
   • the mass of salt
   • the type of beaker
   • the volume of water
   Check

2. 2. In Marcus and Sofia's test, what was the dependent variable?

   • the spatula size
   • the volume of water
   • the mass of salt that dissolved
   • the room temperature
   Check

3. 3. Marcus and Sofia's results: 50 cm³ of water dissolved 20 g of salt, and 100 cm³ dissolved 36 g. What do these results show?

   • Volume has no effect.
   • The more water, the more salt dissolves.
   • The more water, the less salt dissolves.
   • Salt never dissolves.
   Check

4. 4. Was Sofia's prediction correct?

   • Yes
   • No
   Check

5. 5. What is a line of best fit?

   • the x-axis
   • a line through zero only
   • a line that shows the trend in the data, with points close to it
   • a line joining every point exactly
   Check

6. 6. What is an anomalous result?

   • the average result
   • the biggest result
   • the first result
   • a result that does not fit the pattern
   Check

7. 7. What should you do with an anomalous result?

   • ignore all results
   • repeat the measurement to check it
   • make the line pass through it
   • use it to draw the line
   Check

8. 8. To compare the solubility of salts X and Y, what is the independent variable?

   • the type of salt
   • the temperature
   • the volume of water
   • the mass dissolved
   Check

9. 9. To compare salts X and Y fairly, what must be kept the same?

   • the type of salt
   • the volume and temperature of the water
   • nothing
   • the mass dissolved
   Check

10. 10. How would you find how much salt X dissolves?

    • filter the dry salt
    • add weighed amounts to a measured volume of water, stirring, until no more dissolves
    • pour all the salt in at once and guess
    • heat it until it boils away
    Check

11. 11. What usually happens to the solubility of a solid when the temperature rises?

    • It becomes zero.
    • It never changes.
    • It increases.
    • It always decreases.
    Check

12. 12. Two solubility curves cross. What does the crossing point show?

    • the temperature at which both salts have the same solubility
    • where both salts are insoluble
    • the melting point of salt
    • the boiling point of water
    Check

13. 13. Why should solubility be measured in g per 100 g of water?

    • because 100 is a nice number
    • it is required by law
    • it makes salt dissolve faster
    • so results can be compared fairly
    Check

14. 14. Why did Marcus use a top pan balance?

    • to measure volume
    • to measure the mass of salt added
    • to measure temperature
    • to stir the water
    Check

15. 15. Marcus's table says 60 cm³ of water dissolved 26 g, but on his graph he plotted 18 g at 60 cm³. Which point is plotted wrongly?

    • the 60 cm³ point
    • the 100 cm³ point
    • the 40 cm³ point
    • the 10 cm³ point
    Check

16. 16. Look at the students' results for copper sulfate. Which result doesn't fit the pattern?

    • 22 g at 20 °C
    • 46 g at 70 °C
    • 30 g at 60 °C
    • 58 g at 80 °C
    Check

17. 17. Look at the students' results. What interval did they use between temperatures?

    • 60 °C
    • 20 °C
    • 10 °C
    • 5 °C
    Check