1. 1
   An environmental engineer at a coal-fired power station bubbles waste flue gas through limewater to test for acidic pollutant gases, and the limewater turns cloudy. The flue gas is known to contain sulfur dioxide, a non-metal oxide.

   (a)

   How would sulfur dioxide be classified?

   [1 mark]

   • AA basic oxide
   • BAn acidic oxide
   • CAn amphoteric oxide
   • DA neutral oxide

   (b)

   Which other common flue gas is also classified as an acidic oxide, contributing to global warming?

   [1 mark]

   • ACopper(II) oxide
   • BCalcium oxide
   • CCarbon dioxide
   • DSodium oxide

   (c)

   The power station uses calcium oxide powder in its scrubbing system to remove the sulfur dioxide from the flue gas. Explain, in terms of the properties of the two oxides, why calcium oxide is effective at removing sulfur dioxide.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A ceramics manufacturer heats copper(II) oxide powder, a metal oxide, with dilute hydrochloric acid and observes the powder dissolving to form a blue solution.

   (a)

   How would copper(II) oxide be classified based on this reaction?

   [1 mark]

   • AAn acidic oxide
   • BA non-metal oxide
   • CA neutral oxide
   • DA basic oxide

   (b)

   Which products would be expected to form when copper(II) oxide reacts with hydrochloric acid?

   [1 mark]

   • ACopper metal and oxygen gas
   • BCopper(II) chloride and water
   • CCopper(II) chloride and hydrogen gas
   • DCopper(II) oxide is unreactive with acids

   (c)

   The manufacturer also has a sample of silicon(IV) oxide, a non-metal oxide used in some ceramic glazes. Predict whether silicon(IV) oxide would react with dilute hydrochloric acid in the same way as copper(II) oxide, explaining your reasoning in terms of metallic and non-metallic character.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A materials science student is given four unlabelled white oxide powders, formed from elements across the same period of the Periodic Table, and asked to classify each as metallic or non-metallic character based on how the oxide reacts with acid and alkali. One oxide, from a Group I metal, reacts readily with acid but not with alkali. Another oxide, from a Group VI non-metal, reacts with alkali but not with acid.

   (a)

   Explain what these results indicate about the position of the two elements in the period.

   [3 marks]

   (b)

   A third oxide in the student's set, from an element between Group I and Group VI in the same period, reacts with both the acid and the alkali. Identify what type of oxide this must be, name two elements whose oxides commonly show this behaviour, and explain how this result fits with the general trend of decreasing metallic character across the period.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A school science department is designing a demonstration for open day, comparing the oxides of sodium, magnesium, aluminium and sulfur, all elements from the same period, to show students the trend from metallic to non-metallic character.

   (a)

   Explain how the department could use reactions with dilute hydrochloric acid and dilute sodium hydroxide solution to classify each oxide, and predict the expected result for each of the four oxides.

   [6 marks]

   (b)

   A visiting student asks why aluminium oxide behaves differently from both magnesium oxide and sulfur's oxide in the demonstration. Using ideas about electronic configuration and position in the Periodic Table, explain why aluminium's oxide shows amphoteric behaviour while its neighbours show only basic or only acidic behaviour.

   [6 marks]

   Total for question 4: 12 marks

End of questions