OCR GCSE Combined Science A (Gateway) Chemistry Paper 10 Higher June 2022 question paper J250/10

In the UK, one person produces about 9.5 × 10³ kg of carbon dioxide per year.

One tree can take in 15 kg of carbon dioxide per year.

Approximately how many of these trees are needed to reduce one person’s yearly carbon dioxide output to zero?

A 15

B 650

C 1600

D 140 000

The diagram shows how crude oil is separated into its fractions in a fractionating column.

Gases

What is the physical state of the crude oil as it enters the fractionating column?

A Aqueous

B Gas

C Liquid

D Solid

Which compound is an alkane?

A C₆H₈

B C₇H₁₂

C C₈H₁₆

D C₉H₂₀

Sulfur dioxide, SO₂, reacts with oxygen, O₂, to make sulfur trioxide, SO₃, to form a dynamic equilibrium.

Which statement describes the reaction at equilibrium?

A Rate of forward reaction < rate of backward reaction

B Rate of forward reaction > rate of backward reaction

C Rate of forward reaction = rate of backward reaction

D Rate of forward reaction ~ rate of backward reaction

The equation shows the extraction of iron, Fe, from an oxide of iron, X, using carbon, C.

2X + 3C → 4Fe + 3CO₂

What is the formula of X ?

A FeO

B Fe₂O

C Fe₂O₃

D Fe₄O₆

The graph shows how the amounts of carbon dioxide, nitrogen and oxygen in the Earth’s early atmosphere may have changed over time.

How many years ago does the graph suggest that photosynthesis started to happen?

A 1.2–1.6 billion years ago

B 2.2–2.6 billion years ago

C 3.2–3.6 billion years ago

D 4.0–4.4 billion years ago

This question is about the Group 7 elements.

Table 11.1 shows some information about the Group 7 elements.

Table 11.1

Complete the table by predicting the appearance of astatine at room temperature.

Write your answer in the box in Table 11.1.

The sizes of the molecules are measured in picometres (pm).

What is the size of a fluorine molecule in metres (m)?

Tick (✓) one box.

Which element has a molecule that is closest to twice the size of a molecule of fluorine?

Tick (✓) one box.

Use Table 11.1 to complete the x axis and plot a line graph of the boiling points of fluorine, chlorine, iodine and astatine against the size of their molecules.

Draw a line of best fit.

Use your graph to predict the boiling point of bromine.

Table 11.1 is repeated below.

Table 11.1

A student thinks that fluorine molecules have the weakest intermolecular forces.

Give two reasons why they are correct.

Use data from Table 11.1.

Describe one similarity and one difference in the arrangement of electrons in atoms of fluorine and chlorine.

The processing of crude oil by the petrochemical industry can be shown by different experiments.

The diagram shows how crude oil can be separated into its fractions.

The crude oil is heated. Different fractions are collected at different temperatures.

What is the name of this separation technique?

Explain how a fraction is separated and collected in the experiment.

A fraction with a boiling point of about 10 °C is not collected in the experiment.

How could the experiment be improved so this fraction is collected?

The table shows the temperatures at which four different fractions are collected.

Which statements about the fractions are true, and which are false ?

Tick (✓) one box in each row.

A student investigates the rate of reaction between large pieces of calcium carbonate and dilute hydrochloric acid.

Fig. 13.1 shows two different experiments the student could use. In both experiments the mass decreases as the reaction progresses.

Fig. 13.1

The equation shows the reaction between calcium carbonate and hydrochloric acid.

Use this equation to explain why the mass decreases as the reaction progresses.

The student decides to use Experiment 2 because they think it will produce more accurate results than Experiment 1.

Explain why the student is correct.

The student repeats Experiment 2 with smaller pieces of calcium carbonate to see how this changes the rate of the reaction.

Describe two variables the student must keep the same in this experiment.

Describe and explain the effect of using smaller pieces of calcium carbonate on the rate of the reaction.

For many years it was thought that the Group 0 elements were completely unreactive.

However, more recently, scientists have been able to react some of the Group 0 elements with fluorine.

The table shows information about some of the compounds Group 0 elements make with fluorine.

Give a reason why the Group 0 elements are usually described as unreactive.

Give a reason why scientists have used fluorine to make compounds of the Group 0 elements.

Xenon difluoride, XeF₂, is a solid at room temperature. It melts at 129 °C and boils at 155 °C. It does not conduct electricity in any state.

Suggest the structure of xenon difluoride, XeF₂.

Give two reasons for your answer in (c)(i).

Describe how the trend in reactivity of the Group 0 elements is linked to the size of the atoms.

Ethanol, C₂H₅OH, can be made by reacting ethene, C₂H₄, with steam, H₂O.

The forward reaction is exothermic.

State Le Chatelier’s principle.

As the temperature of the reaction is increased does the amount of ethanol decrease, increase or stay the same?

Explain your answer to (b)(i).

As the pressure of the reaction is increased does the amount of ethanol decrease, increase or stay the same?

Explain your answer to (c)(i).