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