1.12 Group 0: the noble gases
6 exam questions worth 11 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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Why are the noble gases unreactive?
Choose one answer.
Correct Not quite: the answer is Their atoms have a full outer shell of electrons
Mark scheme
B
Model answer
B: a full outer shell is stable, so the atoms do not easily lose, gain or share electrons.
Explain why argon is used in filament lamps.
Mark scheme
- argon is inert / unreactive (1)
- so the hot filament does not react / burn (1)
Model answer
Argon is inert, so the very hot filament does not react with it, whereas in air it would burn in oxygen.
The boiling point of argon is −186 °C and the boiling point of xenon is −108 °C.
Krypton is between argon and xenon in Group 0. Predict the boiling point of krypton and explain your prediction.
Mark scheme
- any value between −185 °C and −109 °C (actual −153 °C) (1)
- boiling point increases down the group, and krypton is between argon and xenon (1)
Model answer
About −150 °C: boiling points increase down Group 0, so krypton must be between argon and xenon.
Give two reasons why helium is used in party balloons instead of hydrogen.
Mark scheme
- helium is less dense than air (so the balloon floats) (1)
- helium is non-flammable / unreactive, but hydrogen is flammable (1)
Model answer
Helium is less dense than air, so the balloon floats, and it is non-flammable, while hydrogen could catch fire.
Describe and explain the trend in boiling points down Group 0.
Mark scheme
- boiling point increases down the group (1)
- atoms get larger / relative atomic mass increases, so forces between atoms are stronger (1)
Model answer
Boiling points increase down the group, because the atoms get larger, so the forces between them are stronger.
Neon has atomic number 10.
Give the electronic structure of neon and explain why neon does not form molecules.
Mark scheme
- 2.8 (1)
- full outer shell, so it does not need to share electrons / does not bond (1)
Model answer
Neon is 2.8. Its outer shell is full, so it does not share electrons to form bonds and exists as single atoms.
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