OCR GCSE Combined Science B (21st Century) Paper 3 June 2025 question paper

Alex uses scalar and vector quantities to describe a journey through their school.

Which statement describes a vector quantity?

Tick (✓) one box.

Complete the table to show which quantities are scalar and which are vector.

Tick (✓) one box in each row.

A distance–time graph of Alex’s journey is shown.

Between points A and B Alex is walking at constant speed.

Describe Alex’s motion between points B and C.

Describe how Alex’s motion between points C and D is different to their motion between points A and B.

A student is researching the structure of different atoms.

Complete the sentences to describe the parts of an atom.

The nucleus of the atom has a negative / neutral / positive charge.

The nucleus is surrounded by negatively charged particles called electrons / neutrons / protons.

The diameter of the nucleus is about a hundredth / hundred-thousandth / millionth of the diameter of the atom.

The table shows information about four different nuclei.

A proton has a charge of +1. A neutron has a charge of 0.

Which nucleus has the largest charge?

Which two nuclei are isotopes of the same element?

Riley and Sam are investigating the speeds of water waves and sound waves.

Fig. 3.1 represents a water wave.

Draw lines to connect each description of the water wave with its correct feature.

Fig. 3.2 shows Riley and Sam standing 50 m from a tall, flat wall. They are doing an experiment to measure the speed of sound in air.

Sam blows a whistle and Riley starts a timer at the same time. Riley stops the timer when she hears the echo from the wall.

When Riley stops the timer, it shows a time of 0.40 seconds.

Calculate the speed of sound in air using this result.

Speed =........ m / s

This calculated speed is not accurate.

The sound produced by the whistle has a frequency of 600 Hz and a wavelength of 0.55 m in air.

Calculate an accurate value of the speed of sound in air using this information.

Use the equation: wave speed = frequency × wavelength

Speed =........ m / s

What step should Riley and Sam take to improve the accuracy of their value for the speed of sound in air?

Tick (✓) one box.

Increase the time between starting and stopping the timer by standing further away from the wall.

Reduce the amplitude of the sound wave by using a quieter whistle.

The water waves are transverse waves and the sound waves are longitudinal waves.

Describe the difference between transverse waves and longitudinal waves.

A teacher uses a rubber band to fire a toy rocket vertically upwards.

The rocket is released and it leaves the rubber band at a speed of 12.0 m / s. The mass of the rocket is 0.125 kg.

Calculate the kinetic energy of the rocket as it leaves the rubber band. Use the equation: kinetic energy = × mass × speed²

Calculate the maximum height reached by the rocket after it leaves the rubber band.

Gravitational field strength = 10 N / kg.

Use your answer to (b)(i).

Suggest one reason why the measured maximum height of the rocket is less than your answer calculated in (b)(ii).

When the rocket falls back to the ground it travels at constant speed for most of the journey.

State the value of the resultant force when the rocket is travelling at a constant speed.

Explain your answer.

This question is about the three states of matter.

Complete the diagram by writing in the names of the changes of state.

Describe the differences in the arrangement and behaviour of the particles in a liquid and a gas.

You can include a diagram to support your answer.

Sasha does an experiment to find the specific latent heat of vaporisation of water.

This is Sasha’s method:

• Put an electric heater inside a container.

• Put some water with a mass of 1.00 kg in the container.

• Switch on the electric heater.

• Start a timer when the water starts boiling.

• Stop the timer after 300 seconds.

• Measure the new mass of the water.

This is Sasha’s results table:

Calculate the power of the electric heater.

Use the equation: energy transferred = power × time

Calculate the specific latent heat of vaporisation of water.

Specific latent heat of vaporisation =........ J / kg

Hiro is investigating how the current through a filament lamp varies with the potential difference across it.

The diagram shows the circuit used by Hiro. The diagram is not complete.

Component 1 is used to measure the potential difference across the filament lamp.

Component 2 is used to change the potential difference across the filament lamp.

Complete the diagram by drawing in the symbols for component 1 and component 2.

The graph shows Hiro’s results.

Use the graph to find the current in the filament lamp when the potential difference across it is 2.4 V.

Calculate the resistance of the filament lamp when the potential difference across it is 2.4 V.

Use your answer to (b)(i).

Explain the relationship between current and potential difference shown on the graph.

Ling wants to find out more about the electricity supply and electricity usage in their home.

Complete the sentences about the UK domestic electricity supply.

The frequency of the supply is........ Hz

The potential difference of the supply is........ V

Domestic electricity supply in the UK provides alternating current.

State the difference between alternating current and direct current.

Ling wants to know how much they spend on boiling water in the kettle each week. Ling estimates that the kettle is switched on for a total of 5 hours each week.

Calculate the cost of using the kettle each week.

Power of the kettle = 2.6 kW. Cost of 1 kWh = 35 p.

Use the Equation Sheet.

Ryan does an experiment to determine the density of a stone sample. They use a 100 cm³ measuring cylinder and a balance that can measure up to 100.0 g.

Fig. 8.1 shows the steps followed by Ryan.

Calculate the volume of the stone, using Fig. 8.1.

What type of error does the balance show in Fig. 8.1 ? Tick (✓) one box.

Calculate the mass of the stone.

Calculate the density of the stone.

Use your answers from (a)(i) and (a)(iii) and the Equation Sheet.

Give your answer to 2 significant figures.

Density =........ g / cm³

Explain two changes that Ryan can make to improve their experiment.

Casey is driving a car along a straight, level road when they see a road block ahead.

The graph shows how the speed of the car changes with time immediately after Casey sees the road block.

While Casey is reacting to the obstruction the car continues to travel at constant speed.

Calculate the distance travelled by the car while Casey is reacting.

Use the Equation Sheet.

The initial kinetic energy of the car is 174 kJ.

When Casey presses the brakes, the braking force acting on the car is 4350 N.

The work done by the brakes to stop the car = the kinetic energy lost by the car.

Calculate the distance travelled while the car is braking.

Use the equation: work done = force × distance

In the village where Casey lives the speed limit has been reduced from 30 mph to 20 mph.

Explain how reducing the speed limit can improve road safety in the village.

Amit does an experiment at room temperature to compare the thermal conductivity of different insulating materials.

This is Amit’s method:

• Place a small metal container inside a large metal container.

• Place some insulating material between them.

• Pour water at a temperature of 80 °C into the small container and place a lid on it.

• Measure the temperature of the water every minute for 30 minutes using a thermometer.

• Repeat the experiment using different insulating materials.

This is the apparatus used:

State two variables that Amit should control in this experiment.

Explain why Amit uses metal containers rather than plastic containers.

The graph shows Amit’s results for one insulating material.

Draw a tangent to the curve at time of 15 minutes.

Calculate the gradient of the tangent drawn in (b)(i).

Gradient =........ °C / minute

Sketch a curve on the graph to show the results of the experiment when a material of higher

thermal conductivity is used.