IGCSE Coordinated Chemistry Workout 17

The diagram shows overlapping circles into which different chemical formulae can be placed.

Which formula can be placed in the shaded area because it has all three properties?

• Br₂

• CO

• Cu

• Na

Which substance is a non-metallic element?

• A

• B

• C

• D

When ammonium sulfate is heated with solution X, ammonia gas is given off. A piece of moist red litmus paper and a piece of moist blue litmus paper are held in the gas.

at is solution X and how does the colour of the litmus paper change?

• X is hydrochloric acid and blue litmus turns red

• X is hydrochloric acid and red litmus turns blue

• X is sodium hydroxide and blue litmus turns red

• X is sodium hydroxide and red litmus turns blue

Ammonia is oxidised as shown. The platinum is chemically unchanged at the end of the reaction.

What is the reason for using platinum?

• to absorb the heat from the reaction

• to filter out oxygen from the air

• to increase the rate of the reaction

• to neutralise the ammonia

Equal masses of magnesium are reacted with 10 cm³ of hydrochloric acid of the same concentration. Hydrogen is produced.

Under which conditions does the hydrogen push the plunger of the syringe out most quickly?

• A

• B

• C

• D

Which household substances are acidic?

• A

• B

• C

• D

Sodium chloride solution is electrolysed and a gas is collected at each electrode. One gas decolourises moist litmus paper, the other gas burns with a pop.

Which statement is correct?

• Chlorine gas is collected at the anode.

• Hydrogen gas is collected at the anode.

• Oxygen gas is collected at the cathode.

• Sodium is collected at the cathode.

A metal oxide is mixed with carbon and heated as shown. The limewater turns cloudy.

Which term describes what happens to the metal oxide?

• combustion

• neutralisation

• reduction

• oxidation

An old iron sword that had been buried under the ground was found covered with a layer of tar. When the tar was removed no rust could be observed on the sword.

What is the reason for this?

• The tar allowed oxygen and water to come into contact with the iron sword.

• The tar allowed oxygen but not water to come into contact with the iron sword.

• The tar prevented oxygen and water from coming into contact with the iron sword.

• The tar prevented oxygen but not water from coming into contact with the iron sword.

Why do farmers add lime to soil?

• It acts as a fertiliser.

• It adds nitrogen to the soil.

• It decreases the pH of the soil.

• It increases the pH of the soil.