CAIE A Level Chemistry 9701 · The Periodic Table: chemical periodicity
Two elements, X and Y, are each added separately to cold water.
X reacts rapidly with cold water, producing a colourless gas that burns with a squeaky pop. The resulting solution turns universal indicator purple.
Y does not react with cold water. When steam is passed over heated Y, a black solid forms and a colourless gas is produced that burns with a squeaky pop.
Suggest the group of the Periodic Table to which X and Y each belong. Explain your reasoning.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Suggest means: Apply what you know to an unfamiliar situation. There may be more than one acceptable answer. Reason from the principle you have learned to the new context, and say which principle you are using.
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