IGCSE Coordinated Chemistry Workout 32

Which statement describes how magnesium atoms and nitrogen atoms combine to form magnesium nitride, Mg₃N₂?

• Each magnesium atom loses three electrons and each nitrogen atom gains two electrons.

• Each magnesium atom loses two electrons and each nitrogen atom gains three electrons.

• Each nitrogen atom loses three electrons and each magnesium atom gains two electrons.

• Each nitrogen atom loses two electrons and each magnesium atom gains three electrons.

How many atoms of metals and of non-metals are shown in the formula Na₂SO₄?

• A

• B

• C

• D

Aqueous copper(II) sulfate is electrolysed using carbon electrodes. What is produced at each electrode?

• A

• B

• C

• D

Aqueous sodium thiosulfate reacts with dilute hydrochloric acid. Increasing the concentration of sodium thiosulfate increases the rate of reaction. Which statement explains this observation?

• The particles are closer together and collide more frequently.

• The particles are closer together and collide with more energy.

• The particles have a greater surface area and collide more frequently.

• The particles have more energy and collide more frequently.

Aluminium reacts with iron (III) oxide, forming iron. The equation for this reaction is shown.

aluminium + iron (III) oxide → iron + aluminium oxide

Which statement explains why this is a redox reaction?

• Aluminium gains oxygen and iron loses oxygen.

• Aluminium is reduced and iron (III) oxide is oxidised.

• Aluminium oxide is oxidised and iron is reduced.

• Iron gains oxygen and aluminium loses oxygen.

The pH of water changes when ammonia is bubbled into it.

What happens to the pH and why?

• A

• B

• C

• D

In which industrial process is sulfuric acid made?

• the catalytic cracking of alkanes

• the Contact process

• the production of iron

• the thermal decomposition of limestone

Part of the Periodic Table is shown. Which description is correct?

• W is a soft solid at room temperature. It has a low melting point and it can act as a catalyst.

• X is a solid at room temperature. It has a high melting point and it can act as a catalyst.

• Y is a solid at room temperature. It forms a coloured vapour and it displaces iodide ions.

• Z is a gas at room temperature. It is very reactive and it has a low boiling point.

Which element is used to extract some metals from their ores?

• carbon

• copper

• iron

• nitrogen

Four solutions are tested with Universal Indicator paper and with anhydrous copper (II) sulfate. Which row shows the observations for pure water?

• A

• B

• C

• D