OCR GCSE Chemistry A (Gateway) Paper 2 Foundation June 2024 question paper J248/02

1h 45m 90 marks

22 questions

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What is the test for oxygen gas?

A Burns with a lilac flame

B Burns with a squeaky pop

C Relights a glowing splint

D Turns limewater milky

$Question 1, shown as an image$

[1]

Answer

A student adds sodium hydroxide solution to copper sulfate solution.

What is the colour of the precipitate made?

A Blue

B Green

C Orange-brown

D White

$Question 2, shown as an image$

[1]

Answer

Which change would decrease the rate of a chemical reaction?

A Adding a catalyst

B Increasing the concentration of the solution

C Increasing the size of the solid pieces

D Increasing the temperature

$Question 3, shown as an image$

[1]

Answer

What is the major source of oxides of nitrogen in the atmosphere?

A Combustion of impurities in coal

B High temperature reactions in car engines

C Incomplete combustion of fossil fuels

D Industrial processes such as metal extraction

$Question 4, shown as an image$

[1]

Answer

How many different monomers (nucleotides) is DNA made from?

A 2

B 3

C 4

D 5

$Question 5, shown as an image$

[1]

Answer

What is the functional group in an alcohol molecule?

A –C–H

B –C=C–

C –COOH

D –O–H

$Question 6, shown as an image$

[1]

Answer

What is the balanced equation for the reaction of sodium with oxygen?

$Question 7, shown as an image$

[1]

Answer

Which row describes the three halogens at room temperature?

	Chlorine Bromine Iodine
A	green gas orange-brown gas grey solid
B	green gas orange-brown liquid grey solid
C	green gas orange-brown liquid purple gas
D	green liquid orange-brown liquid grey solid

$Question 8, shown as an image$

[1]

Answer

The table shows the results of the reactions between four metals and their metal oxides.

Key: ✓ = reaction ✗ = no reaction

What is the correct order of reactivity of the metals, from the most reactive to the least reactive?

A W, Y, X, Z

B W, Z, Y, X

C Z, X, Y, W

D Z, Y, X, W

$Question 9, shown as an image$

[1]

Answer

Two chemicals react together over time to make a cloudy precipitate.

What is the best method for determining the rate of reaction?

A Measure the loss in mass using a balance.

B Use a gas syringe.

C Use a pH meter.

D Use the disappearing cross experiment.

$Question 10, shown as an image$

[1]

Answer

Which polymer would be best for making a washing up bowl?

Polymer	Maximum useable temperature (°C)	Strength
A	38	high
B	85	low
C	110	high
D	160	low

$Question 11, shown as an image$

[1]

Answer

4.8 dm³ of air contains 0.12 dm³ of water vapour. 12

What is the percentage of water vapour in the air?

A 0.3%

B 2.5%

C 12.0%

D 97.5%

$Question 12, shown as an image$

[1]

Answer

Magnesium carbonate, MgCO₃, decomposes to make magnesium oxide, MgO.

Carbon dioxide is a waste product.

$Question 13, shown as an image$

Relative formula mass (M_r): MgO = 40.3 CO₂ = 44.0

What is the atom economy of the reaction?

$Question 13, shown as an image$

A 47.8%

B 52.2%

C 91.6%

D 109.0%

$Question 13, shown as an image$

[1]

Answer

Which substance is an unsaturated hydrocarbon?

A CH₄

B C₂H₆

C C₃H₆

D C₃H₈

$Question 14, shown as an image$

[1]

Answer

What happens when liquid bromine, Br₂, boils?

A Covalent bonds break

B Electrostatic forces break

C Intermolecular forces break

D Ionic bonds break

$Question 15, shown as an image$

[1]

Answer

This question is about compounds of carbon.

(a)

The first member of the alkane homologous series is methane, CH₄.

State the name of the next alkane in the homologous series, C₂H₆.

[1]

Answer

(b)

Complete the balanced symbol equation for the complete combustion of methane.

[2]

Answer

(c)

Carbon monoxide, CO, is made in the incomplete combustion of methane.

State why carbon monoxide is a problem.

[1]

Answer

(d)

[3]

Answer

(e)

Fractional distillation produces a large amount of long chain molecules.

There is a high demand for short chain molecules.

$Question 16, shown as an image$

combustion cracking oxidation polymerisation

[1]

Answer

(f)

[4]

Answer

(a)

Explain why the iron nail in test tube 1 is the only nail that rusts.

[2]

Answer

(b)

The student sets up another test tube as shown in Fig. 17.2.

Fig. 17.2

The mass of this iron nail was unchanged after a week.

Explain why.

[2]

Answer

(c)

Table 17.1 shows some properties of three different materials.

Table 17.1

	Ceramic	Metal	Polymer
Melting point (°C)	2200	1083	204
Strength (MPa)	416	69	27
Relative thermal conductivity	18	388	0.21

(c)(i)

The diagram shows a pan of boiling water.

Which material would you choose to make the base of a pan?

Explain your choice using the information in Table 17.1.

Material........

Explanation........

........

[3]

Answer

(c)(ii)

Estimate how many times higher the melting point of the ceramic is compared to the polymer.

You will need to round the melting points to 1 significant figure.

[1]

Answer

(d)

[2]

Answer

(a)

[3]

Answer

(b)

Complete the table to show the gases in the Earth’s atmosphere today.

Gas	Percentage in Earth’s atmosphere (%)
......................................................................	78
......................................................................	21
Carbon dioxide / noble gases / water vapour	1

[2]

Answer

(c)

Clean water is essential for life.

(c)(i)

State the name used for water that is safe to drink.

[1]

Answer

(c)(ii)

Explain why chlorine is added to water to make it safe to drink.

[1]

Answer

(c)(iii)

Describe the test for chlorine gas.

[2]

Answer

(d)

(d)(i)

There is a link between the amount of sulfur dioxide in the atmosphere and the amount of acid rain.

Complete the table by correctly identifying which word finishes each sentence.

Put one tick (✓) in each row.

[3]

Answer

(d)(ii)

State one problem caused by acid rain.

[1]

Answer

A student investigates the neutralisation reaction between sodium hydroxide solution and dilute hydrochloric acid.

They do a titration experiment.

The diagram shows the apparatus they use.

(a)

What is the name of the piece of equipment labelled X ?

[1]

Answer

(b)

The student places the conical flask on a white tile.

Explain why.

[1]

Answer

(c)

The student adds the alkali to the acid drop by drop near the endpoint of the titration.

Explain why.

[1]

Answer

(d)

The neutralisation reaction between sodium hydroxide solution, NaOH, and dilute hydrochloric acid, HC l, makes a salt and water.

Write the balanced symbol equation for the reaction.

[2]

Answer

(e)

In another neutralisation reaction dilute sulfuric acid, H₂SO₄, reacts with potassium hydroxide solution, KOH.

$Question 19, shown as an image$

Calculate the mass of potassium sulfate, K₂SO₄, that could be made from 6.54 g of dilute sulfuric acid, H₂SO₄.

Give your answer to 3 significant figures.

Relative atomic mass (A_r): H = 1.0 K = 39.1 O = 16.0 S = 32.1

[4]

Answer

A student investigates the reaction between marble chips and dilute hydrochloric acid.

The diagram shows their experiment.

The student measures the volume of carbon dioxide gas collected in the measuring cylinder every 30 seconds.

(a)

Which other piece of equipment could the student use to measure the volume of carbon dioxide gas collected?

Tick (✓) one box.

$Question 20, shown as an image$

[1]

Answer

(b)

(b)(i)

Plot the results from the table on the graph.

[3]

Answer

(b)(ii)

[1]

Answer

(b)(iii)

State the time when the reaction stops.

[1]

Answer

(b)(iv)

The student observes that there are still some marble chips in the conical flask when the reaction stops.

Explain why the reaction stops.

[1]

Answer

(c)

* Another student reacts dilute hydrochloric acid with magnesium.

The student does two experiments.

In each experiment they use the same

• concentration of dilute hydrochloric acid

• mass of magnesium.

The table shows their results.

	Experiment 1	Experiment 2
Magnesium	large pieces	small pieces
Temperature of dilute hydrochloric acid (°C)	20	42
Reaction time (s)	225	25

Describe and explain the difference in the rate of reaction between the two experiments. Use the student’s results and the reacting particle model.

State how the student’s experiment could be improved.

[6]

Answer

(a)

The table shows some properties of four Group 1 elements.

Element	Density (g / cm³)	Melting Point (°C)	Boiling Point (°C)
Lithium	0.53	180	1342
Sodium	0.97	98	883
Potassium	0.86	63	759
Rubidium	1.53	39	688

(a)(i)

State one trend in the properties of the Group 1 elements shown in the table.

[1]

Answer

(a)(ii)

Caesium is below rubidium in Group 1.

Predict the melting point of caesium using the information in the table.

[1]

Answer

(b)

The Group 1 elements all react with Group 7 elements to form ionic compounds.

(b)(i)

Explain why the Group 1 elements all react in the same way.

[1]

Answer

(b)(ii)

The Group 1 elements become more reactive down the group.

Explain why.

[3]

Answer

(b)(iii)

Sodium reacts with bromine, Br₂, to make sodium bromide, NaBr.

Write the balanced symbol equation for this reaction.

[2]

Answer

(c)

[2]

Answer

Ammonia is made in the Haber process. This is the balanced symbol equation for this process.

$Question 22, shown as an image$

(a)

The reversible reaction is carried out in a closed system.

(a)(i)

State how you can tell that this reaction is reversible.

[1]

Answer

(a)(ii)

What is a closed system ?

[1]

Answer

(a)(iii)

If dynamic equilibrium is reached, which of these statements are correct?

Tick (✓) two boxes.

$Question 22, shown as an image$

[2]

Answer

(b)

The reaction in the Haber process can be reversed by altering the reaction conditions.

The reaction can be reversed by altering the pressure.

Suggest one other change that could be made to the reaction conditions.

[1]

Answer

(c)

A factory predicts they will make 800 tonnes of ammonia.

They actually make 620 tonnes of ammonia.

Calculate the percentage yield of ammonia.

[2]

Answer

(d)

State why the reaction in the Haber process has an atom economy of 100%.

Use the balanced symbol equation.

[1]

Answer

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OCR J248 · Paper 2

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19

Question 20

Question 21

Question 22