IGCSE Coordinated Chemistry Workout 18

An acid is added to an alkali until the final solution is just neutral. The reaction is exothermic.

Which graph shows how the temperature changes as the acid is added to the alkali?

• A

• B

• C

• D

The diagram represents the arrangement of atoms in a molecule of a compound.

What is the molecular formula of the compound?

• CH₂

• C₃H₆

• C₃H₈

• C₆H₃

Small amounts of barium chloride and sand are shaken with separate samples of water in two test-tubes. The test-tubes are left to stand for 24 hours.

Which diagram shows how the test-tubes appear at the end?

• A

• B

• C

• D

Substance Q is used to make a cooking pan. What are the properties of substance Q?

• high melting point and high thermal conductivity

• high melting point and low thermal conductivity

• low melting point and high thermal conductivity

• low melting point and low thermal conductivity

The experiment shown is used to investigate the properties of solid X. At first, the lamp does not light. On heating, solid X melts and the lamp lights.

What type of substance is X?

• a compound of a metal and a non-metal

• a compound of two non-metals

• a metallic element

• a non-metallic element

The table shows the temperature of some water before and after a solid is dissolved in it.

Which change is the most exothermic?

• A

• B

• C

• D

The diagram shows the circuit for electrolysing concentrated aqueous copper (II) bromide. Copper(II) bromide is similar to copper (II) chloride.

Which row describes the products at each electrode?

• bromine at the cathode and copper at the anode

• copper at the cathode and bromine at the anode

• copper at the cathode and oxygen at the anode

• oxygen at the cathode and copper at the anode

Hydrogen can occur as an atom, an ion and a molecule.

Which row represents these particles?

• A

• B

• C

• D

Substance X does not react with dilute acid. Substance Y reacts with dilute acid, forming a gas. The graph shows the results of two experiments.

What do these results show?

• X is a catalyst and is quickly used up in the reaction.

• X is a catalyst and is not used up during the reaction.

• X is not a catalyst and is quickly used up in the reaction.

• X is not a catalyst and is not quickly used up in the reaction.

The apparatus below is used to investigate the speed of a chemical reaction. For which reaction is the apparatus suitable?

• gas E + gas F → liquid G only

• solid H + solution I → solution J only

• solid K + solution L → solution M + gas N

• solution P + solution Q → solid R + solution Q