IGCSE Coordinated Chemistry Workout 9

Element X can form four covalent bonds. Element Y can form two covalent bonds. What is the simplest formula of the compound formed by X and Y?

• XY₂

• X₂Y

• X₂Y₄

• X₄Y₂

Element X forms a basic oxide. How should X be described?

• A

• B

• C

• D

Catalytic cracking is useful in the petrochemical industry.

Which two of the listed equations are possible cracking reactions?

1 2C₈H₁8 → C₁₆H₃₄ + H₂

2 C₁₀H₂₀ + H₂ → C₁₀H₂₂

3 C₁₀H₂₂ → C₁₀H₂₀ + H₂

4 C₁₀H₂₂ → C₈H₁₈ + C₂H₄

• 1 and 3

• 1 and 4

• 2 and 3

• 3 and 4

Why is carbon used to extract some metals from their oxide ores?

• It oxidises the ore by removing oxygen.

• It prevents the oxygen of the air reacting with the ore.

• It reacts with impurities in the ore.

• It reduces the ore by removing oxygen.

Which process can be used to produce sodium and chlorine from the compound sodium chloride?

• cracking

• distillation

• electrolysis

• filtration

An acid reacts with an alkali. Which type of reaction and which temperature change takes place?

• A

• B

• C

• D

What is used to test for ammonia gas?

• a lighted splint

• aqueous sodium hydroxide

• damp red litmus paper

• limewater

An element present in fuels such as coal and coke is ……1…….

When the fuel is ……2…… this element reacts to form an ……3…… gas that is harmful to trees. Which words correctly complete gaps 1, 2 and 3?

• A

• B

• C

• D

Biogas is a mixture of gases. It is used as a fuel. The diagram shows a biogas generator. Which gas in the mixture burns?

• methane

• nitrogen

• oxygen

• water vapour

Substance X is an ionic compound. Which diagrams are correct for X?

• P and Q only

• P and R only

• R and Q only

• P, Q and R