1. 1
   A school laboratory technician drops small pieces of potassium, then sodium, then calcium into separate beakers of cold water, observing each metal fizzing, moving across the surface and, in the case of potassium, catching fire with a lilac flame.

   (a)

   Which metal in this series reacts least vigorously with cold water?

   [1 mark]

   • ACalcium
   • BSodium
   • CPotassium
   • DThey all react with identical vigour

   (b)

   The technician identifies the gas given off in each reaction by holding a lit splint near the mouth of each beaker and hearing a squeaky pop. What is this gas?

   [1 mark]

   • AChlorine
   • BOxygen
   • CCarbon dioxide
   • DHydrogen

   (c)

   State the products formed when potassium reacts with cold water, and name the other substance produced alongside hydrogen gas.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An archaeology museum displays ancient artefacts made from gold, silver, copper and iron. The curator notes that the gold artefacts, thousands of years old, are still bright and untarnished, while the iron artefacts are heavily corroded.

   (a)

   Which statement best explains why gold is found in an unreacted, metallic state in the ground far more often than iron?

   [1 mark]

   • AGold has a lower density than iron
   • BGold is more reactive than iron, so it corrodes faster
   • CGold is very unreactive/low in the reactivity series, so it does not readily form compounds
   • DGold is magnetic, so it resists corrosion

   (b)

   The curator explains that historically, iron tools could only be extracted and used once people developed methods to obtain the metal from its ore, unlike gold which could be found as the metal itself. Which of these metals, in order from the reactivity series, is the most reactive?

   [1 mark]

   • ACopper
   • BIron
   • CSilver
   • DGold

   (c)

   Explain, in terms of the reactivity series, why iron and copper had to be extracted from their ores by early metalworkers, whereas gold could be used directly from naturally occurring metal deposits.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student carries out an experiment adding excess powdered magnesium, zinc, iron and copper separately to test tubes of dilute hydrochloric acid, and times how long it takes for each metal to stop producing bubbles of gas. Magnesium reacts fastest, then zinc, then iron, while copper produces no bubbles at all.

   (a)

   Deduce the order of reactivity of these four metals, from most to least reactive, and explain how the results support this order.

   [3 marks]

   (b)

   The student then adds a piece of magnesium ribbon to a solution of zinc sulfate, and separately adds a piece of copper to a solution of iron(II) sulfate. A grey coating appears on the magnesium ribbon, but no visible change occurs with the copper. Explain these observations in terms of the reactivity series and displacement reactions, referring to the tendency of metals to form positive ions.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A materials science teacher demonstrates that aluminium window frames survive outdoors for decades without visible corrosion, even though aluminium is positioned above zinc and iron in the reactivity series and would therefore be expected to react more readily.

   (a)

   Explain, in terms of the reactivity series and the behaviour of aluminium, why aluminium appears far less reactive in everyday use than its position in the reactivity series would suggest.

   [6 marks]

   (b)

   The teacher then asks students to design a set of experiments, using only dilute hydrochloric acid, cold water and displacement reactions with aqueous metal salts, to place five unlabelled metal samples (which the students know to be magnesium, zinc, iron, copper and silver, but not in which order) into the correct order of reactivity. Describe how the students could use these methods to deduce the order of reactivity of the five metals.

   [6 marks]

   Total for question 4: 12 marks

End of questions