CAIE A Level Chemistry 9701 · Group 2
Nitrates of the Group 2 metals, magnesium to barium, decompose on heating to give the metal oxide, nitrogen dioxide and oxygen. Explain why the thermal stability of these nitrates increases down the group. In your answer, include the equation for the thermal decomposition of the nitrate of a Group 2 metal, M.
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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