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6. What is the temperature gradient in a fractioning column?

  • Hot at the bottom and cooler as you go up
  • Cold at the bottom and hotter as you go up
  • Warm at the bottom and stays warm as you go up

7. How can you test for the purity of a sample?

  • Measure its boiling or melting point
  • See if it has evaporated
  • Check if Co2 is present

8. Which is a correct statement about incomplete combustion?

  • It is cleaner than complete combustion
  • Poisonous carbon monoxide may be produced
  • It releases more energy than complete combustion

9. What is the name of the alkane which has the formula C4H10?

  • Butane
  • Methane
  • Octane

10. Looking at the chemical formulae of these compounds, which is an alkane?

  • C5H10
  • C3H8
  • C2H4

11. When hydrocarbons like the alkanes burn in plenty of air, what type of reaction takes place?

  • Incomplete combustion
  • Complete combustion
  • Thermal decomposition

12. Alkanes are saturated hydrocarbons. What does this mean?

  • They are very reactive
  • All C atoms are bonded by single covalent bonds
  • There are some C=C double bonds present in the molecule

13. How do you test for an alkene?

  • They turn bromine water colourless
  • They turn limewater cloudy
  • They turn universal indicator purple

14. The longer the hydrocarbons the...

  • Higher the boiling points
  • Lower the boiling points
  • Cooler the boiling points

15. What is the name of the reaction to produce ethanol from sugar?

  • Fermentation
  • Polymerisation
  • Reduction

16. A student made ethanol from sugar. What change is seen in the limewater?

  • Turns cloudy, because Carbon dioxide is produced
  • Bubbles appear because oxygen is present
  • The limewater dissapear because the reaction is finished

17. What is cracking?

  • Splitting up long-chain hydrocarbons into short-chain hydrocarbons
  • Removing the covalent bond into an ionic bond
  • Neither

18. How was crude oil formed?

  • The Energy left over from over millions of years ago
  • From the remains of dead plants and animals over millions of years ago
  • The food left over from humans over millions of years ago

19. Which of the following is an alkane?

  • Cyclohexane
  • Propene
  • Ethanol

20. What is thermal decomposition?

  • Breaking molecules down by heating them
  • Breaking molecules down by evaporating them
  • Breaking atom structures down with covalent bonding