CAIE A Level Chemistry 9701 · Group 17
The elements of Group 17 react with hydrogen to form hydrogen halides, and the hydrogen halides decompose on heating.
(a) State and explain the trend in the oxidising power of the halogen elements down the group.
(b) State and explain the trend in the thermal stability of the hydrogen halides down the group.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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