OCR GCSE Combined Science B (21st Century) Paper 6 June 2024 question paper

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Question

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(a)

Table 1.1 shows the diameters of some particles.

Table 1.1

Particle	Diameter (m)
Carbon atom	1.54 × 10^–10
Fullerene molecule	1.10 × 10^–9
Silver atom	2.88 × 10^–10
Platinum nanoparticle	1.00 × 10^–8

(a)(i)

Which two particles have diameters with the same order of magnitude?

[1]

Answer

(a)(ii)

Write down the particles in order of diameter.

Smallest........

$Question 1, shown as an image$

[2]

Answer

(b)

Nanoparticles make effective catalysts because they have a high surface area to volume ratio.

Table 1.2 shows the surface area to volume ratio of some different sized particles.

Table 1.2

	Nanoparticle	Particle of Fine Powder	Particle of Coarse Powder
Size of Particle (nm)	60	600	6000
Surface Area to Volume Ratio	0.1	0.01	0.001

Describe the relationship between the size of a particle and its surface area to volume ratio.

[2]

Answer

(c)

The nanoparticle shown is a cube. This nanoparticle has a volume of 1000 nm³.

NOT TO SCALE

Calculate the surface area of the nanoparticle.

Use the formula: surface area = 6 × (h × w)

[3]

Answer

A student is investigating the reaction between calcium hydroxide and hydrochloric acid.

$Question 2, shown as an image$

(a)

They want to find the temperature change during the reaction.

1 g masses of solid calcium hydroxide are added one by one to 50 cm³ of dilute hydrochloric acid in a plastic cup.

Describe two measurements the student needs to make and the apparatus needed to make the measurements.

[2]

Answer

(b)

The table shows the student’s results:

Mass of calcium hydroxide (g)	Temperature of hydrochloric acid (C)
0	22.0
1	29.5
2	37.0
3	44.5
4	52.0
5	59.5

Plot the results from the table on the graph.

Two points have already been plotted.

[2]

Answer

(c)

Draw a line of best fit.

[1]

Answer

(d)

Which relationship describes the graph?

$Question 2, shown as an image$

y = mx y = mx² y = mx + c y = mx – c

[1]

Answer

(e)

Calculate the change in temperature if 3.8 g of calcium hydroxide is added to the hydrochloric acid.

Use the graph.

Temperature change =........ maths symbol C

[2]

Answer

(f)

Calculate the change in thermal energy when 3.8 g of calcium hydroxide is added to 50 cm³ of (f) hydrochloric acid.

Use the formula:

Change in thermal energy (J) = 4.2 × temperature change ( maths symbol C) × mass of hydrochloric acid (g)

1 cm³ hydrochloric acid = 1.02 g

[3]

Answer

Atoms are made up of a small nucleus containing protons and neutrons. The rest of the space contains electrons.

(a)

Complete the table to show the relative masses and charges of the three particles in the atom.

Particle	Relative Mass	Relative Charge
Proton	.................................	.................................
Neutron	.................................	.................................
Electron	.................................	.................................

[3]

Answer

(b)

A student builds a model of an atom.

They use a tennis ball with a diameter of 6.7 cm to represent the nucleus in the model.

The diameter of an atom is 1 × 10⁵ times bigger than the diameter of its nucleus.

Calculate the diameter of the model of the atom.

Give your answer in m.

[2]

Answer

(c)

The number of protons, neutrons and electrons in an atom or an ion can be calculated using the atomic number and relative atomic mass of the element.

Complete the table to show the number of each particle present in a phosphorus atom and a sodium ion.

Use the Data Sheet.

[3]

Answer

(d)

The properties of elements depend on the electron arrangements of their atoms.

The electron arrangement of magnesium is 2.8.2. The electron arrangement of fluorine is 2.7.

Explain why magnesium is a metal and fluorine is a non-metal.

[2]

Answer

The diagram shows the structure of a metal.

Electrons from outer shell of metal atoms

Metal ions

(a)

Explain why metals are good electrical conductors, malleable, and have high melting points.

Good electrical conductors........

Malleable........

High melting points........

[3]

Answer

(b)

A student does some experiments to find the reactivities of some metals.

In one experiment, they add a piece of magnesium to a blue aqueous solution of copper ions.

They see a reddish metal formed and the blue solution fades to colourless.

$Question 4, shown as an image$

Explain how this reaction shows that magnesium is more reactive than copper.

[2]

Answer

(c)

(c)(i)

Write a balanced ionic equation for the reaction between solid copper and aqueous silver ions.

[2]

Answer

(c)(ii)

Write down the metals in order of reactivity.

Most reactive........

Least reactive........

[2]

Answer

The particle models for the different states of matter are shown.

Solid Liquid Gas

(a)

State two limitations of the particle model.

[2]

Answer

(b)

The table gives some information about the movement and arrangement of particles for the different states of matter.

Complete the table.

	Movement of Particles	Arrangement of Particles
Solid	....................................................................	1 Regular 2 Close together
Liquid	....................................................................	1 Random 2 ................................................................
Gas	Move in all directions	1 ................................................................ 2 ................................................................

[4]

Answer

(c)

Explain why heating a solid causes it to change state.

[2]

Answer

(d)

Sulfur dioxide has a melting point of –73 maths symbol C and a boiling point of –10 C.

What is the state of sulfur dioxide at 20 maths symbol C?

[1]

Answer

A student wants to find the concentration of a sodium hydroxide solution. They do a titration using sodium hydroxide solution and 0.010 mol / dm³ dilute hydrochloric acid.

(a)

* Describe how the student can accurately find the concentration of the sodium hydroxide solution, using these solutions.

Include an explanation of how this method gives high quality data.

[6]

Answer

(b)

The table shows the student’s results.

Titration	1	2	3	4	5
Volume of Acid Added (cm³)	27.2	25.4	25.3	25.2	25.2

(b)(i)

Why is the first reading much higher than the others?

[1]

Answer

(b)(ii)

Calculate the mean volume of acid which reacts with the sodium hydroxide solution.

Give your answer to 1 decimal place.

[3]

Answer

(b)(iii)

[2]

Answer

Ammonia is made from nitrogen and hydrogen.

$Question 7, shown as an image$

(a)

(a)(i)

$Question 7, shown as an image$

[1]

Answer

(a)(ii)

Explain why reactions like this never give a 100% yield.

[1]

Answer

(b)

The conditions of the reaction are carefully chosen to produce the best yield as quickly as possible.

The graph shows the effect of temperature and pressure on the yield of ammonia.

(b)(i)

Complete the table to show the effect of changing the conditions on yield and rate of reaction.

Use words from the list.

Increase Decrease No Effect

	Effect on yield	Effect on rate of reaction
Increasing the Temperature	.................................	Increase
Increasing the Pressure	.................................	Increase
Using a Catalyst	.................................	.................................

[4]

Answer

(b)(ii)

Explain why the rate of reaction increases when the temperature and pressure are increased.

Temperature........

Pressure........

[4]

Answer

(c)

Ammonium sulfate, (NH₄)₂SO₄, is used by farmers as a fertiliser.

Ammonia gas is bubbled into dilute sulfuric acid, H₂SO₄, to form an aqueous solution of ammonium sulfate.

Write a balanced symbol equation for the reaction.

Include state symbols.

[2]

Answer

Acids react with some metal compounds to form salts.

(a)

Table 8.1 shows the reactants and products of some of these reactions.

Table 8.1

Acid	Metal Compound	Salt Formed
Hydrochloric acid	Sodium hydroxide	Sodium chloride
Sulfuric acid	Copper oxide	.................................
.................................	Calcium carbonate	Calcium nitrate