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Date May 2017 Marks available 2 Reference code 17M.2.hl.TZ1.8
Level HL Paper 2 Time zone TZ1
Command term Formulate Question number 8 Adapted from N/A

Question

There is concern about damage done to the ozone layer in the stratosphere by jet-propelled aircraft.

Formulate two equations to show how nitrogen(II) oxide, NO, catalyses the destruction of ozone.

[2]
a.

Suggest why the loss of ozone is an international environmental concern.

[2]
b.

Markscheme

NO (g) + O 3 (g) N O 2 (g) + O 2 (g)

N O 2 (g) + O (g) NO (g) + O 2 (g)
OR
N O 2 (g) + O 3 (g) NO (g) + 2 O 2 (g)

 

Allow representation of radicals without  if consistent throughout.

[2 marks]

a.

«loss of ozone» allows UV radiation to penetrate atmosphere/reach earth

UV radiation causes skin cancer
OR
UV radiation causes tissue damage

[2 marks]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Additional higher level (AHL) » Topic 14: Chemical bonding and structure » 14.1 Covalent bonding and electron domain and molecular geometries
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Additional higher level (AHL) » Topic 14: Chemical bonding and structure
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