OCR GCSE Combined Science A (Gateway) Chemistry Paper 4 Foundation June 2023 question paper J250/04

Which part of the Periodic Table contains the most reactive metals?

Which process traps heat from the Sun in the Earth’s atmosphere?

A Combustion

B Displacement

C Greenhouse effect

D Photosynthesis

What is the temperature of the dilute hydrochloric acid shown in the diagram?

The Earth’s atmosphere contains 78% nitrogen and 21% oxygen. The remaining 1% is listed in the table.

What is the percentage of carbon dioxide in the Earth’s atmosphere?

A 0.01%

B 0.04%

C 0.06%

D 0.08%

The table shows the boiling points of three Group 1 elements.

How many of these elements are gases at 700 °C?

A 0

B 1

C 2

D 3

The diagram shows the reaction profile for an uncatalysed reaction.

How does adding a catalyst to the reaction change the reaction profile?

A X is larger

B X is smaller

C Y is larger

D Y is smaller

Which particles do atoms in Group 7 gain when they react?

A Electrons

B Ions

C Neutrons

D Protons

Which reactions can be catalysed by an enzyme?

A Combustion reactions

B Electrolysis of metal ores

C Reactions in biological systems

D Reactions of metals with acids

The reversible reaction.

The reaction of a very reactive metal.

The reaction of a green gas.

The reaction where a more reactive metal displaces a less reactive metal.

The reaction where a metal is extracted using electrolysis.

Fig. 12.1 shows the separation of the chemicals found in crude oil.

Fig. 12.1

Gases

What is the name of the process shown in Fig. 12.1 ?

Crude oil is heated and vaporised as it enters the column.

Describe what happens to the vapours as they rise up the column.

Which of the chemicals separated from crude oil has the smallest molecules?

Tick (✓) one box.

Fig. 12.2 shows the structure of a molecule found in crude oil.

Fig. 12.2

Which words describe the molecule?

Tick (✓) two boxes.

There are other molecules similar to Fig. 12.2 but with different numbers of carbon atoms.

Fig. 12.3 shows how the boiling point of these molecules changes with the number of carbon atoms in the molecule.

Fig. 12.3

Number of carbon atoms in the molecule

Use the graph to estimate the boiling point of the molecule shown in Fig. 12.2.

160 litres of crude oil contains 75 litres of petrol.

Calculate the percentage of petrol in the crude oil.

Give your answer to 2 significant figures.

Lithium, sodium and potassium are metals in Group 1 of the Periodic Table.

Table 13.1 shows the melting points of lithium, sodium and potassium.

Table 13.1

Complete the bar chart to show the melting point of sodium.

State and explain which of the metals lithium, sodium or potassium is the softest. Use information from Table 13.1.

Metal........

Reason........

Lithium, sodium and potassium can be cut with a knife as shown in the diagram.

At first the freshly cut surface looks shiny, but then begins to go dull.

Complete Table 13.2 by estimating the times for lithium and potassium surfaces to go dull.

Table 13.2

Lithium, sodium and potassium are stored in oil to prevent them reacting with gases in the air.

Which gases in the air react with lithium, sodium and potassium?

Tick (✓) two boxes.

14* Cars can burn petrol or diesel as a fuel. The composition of the exhaust fumes depends on the type of fuel used.

The table shows the percentages of some substances found in the exhaust fumes of petrol and diesel cars.

Describe one advantage and one disadvantage of using petrol as a fuel. Use information from the table.

Explain your answer using your knowledge of the environmental problems caused by these substances.

In industry, iron can be extracted from iron ore. Iron ore contains iron oxide, Fe₂O₃.

Iron is extracted from iron oxide by reduction.

The equation for one reaction is

Complete the balanced symbol equation for the reaction.

Why does this reaction happen?

Tick (✓) one box.

Explain how the equation shows that the iron oxide is reduced.

Which chemical reduces the iron oxide, Fe₂O₃?

Tick (✓) one box.

In industry, iron is extracted from iron ore in a blast furnace.

The table shows information about the production of iron in a blast furnace and from recycling.

Give two reasons why it is better to produce iron from recycling than in a blast furnace.

Use the information from the table.

Calculate the mass of iron made from 250 tonnes of iron ore in the blast furnace. Give your answer in kilograms.

(1 tonne = 1000 kg)

The student has difficulty filling the measuring cylinder with water.

They change the measuring cylinder for a different piece of apparatus which allows them to measure the volume of hydrogen more accurately.

Name the piece of apparatus they use and complete the diagram below to show this apparatus.

Name of piece of apparatus........

Complete the balanced symbol equation for the reaction.

The student repeats the experiment. The only difference is they use a higher concentration of acid.

Draw a line on the graph to show the results of this experiment.

If the experiment is repeated at a higher temperature, the rate of reaction increases.

Explain why. Use ideas about particles and collisions.