Matter | OCR GCSE Physics A, Higher tier (J249)
Matter
- 207 questions
- 11 subtopics
- Paper 3
- Paper 3
Matter is examined in Physics A Paper 3.
It covers how the atomic model changed, and the structure of the atom, the size of atoms, and defining density, density of the states of matter, and density calculations, conservation of mass in changes of state, heating a system, and specific heat capacity, calculations with specific heat capacity and latent heat, gas molecules, temperature and pressure, compressing a gas, and changing its volume, doing work on a gas, atmospheric pressure and why it varies with height and floating, sinking and pressure in a liquid.
Sample questions from Matter
Answer each one closed book first, then open the answer.
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How the atomic model changed, and the structure of the atom
Why do accepted scientific models such as the model of the atom change over time?
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New experimental evidence appears that the existing model cannot explain, so the model has to be revised or replaced. -
The size of atoms, and defining density
Why are the sizes of atoms usually written in standard form?
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Their size is about 1 × 10⁻¹⁰ m, which written out in full as a decimal would be a long and awkward number. -
Density of the states of matter, and density calculations
How is the density relationship rearranged to find volume?
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Volume is equal to mass divided by density. -
Conservation of mass in changes of state
What happens to the total mass of a substance when it melts, and why?
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The mass is unchanged, because exactly the same particles are still present and none are created or destroyed. -
Heating a system, and specific heat capacity
A beaker of water is heated steadily. Its temperature rises until it boils and then stops rising. Explain why.
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Before boiling the energy raises the kinetic energy of the particles, but at the boiling point it separates the particles instead, so the temperature holds steady. -
Calculations with specific heat capacity and latent heat
The specific latent heat of vaporisation of water is 2 260 000 J/kg. Calculate the energy needed to boil away 2 kg of water at its boiling point.
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The energy needed is 4 520 000 J. -
Gas molecules, temperature and pressure
Why does a gas spread out to fill any container it is put into?
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Its molecules move randomly at high speed and are not held together, so they spread apart until they meet the walls. -
Compressing a gas, and changing its volume
A sealed bag of crisps swells as it is carried up a mountain. Explain why.
Show the answer
The air pressure outside falls with height while the gas inside keeps pushing outwards, so the gas expands.
The 11 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| How the atomic model changed, and the structure of the atom | The Thomson, Rutherford and Bohr models and Chadwick's neutron, the alpha scattering experiment of Geiger and Marsden and what it showed, the nuclear atom and its size, why models change, and hypotheses, testing theories, peer review and publishing results. | 24 |
| The size of atoms, and defining density | The typical size of atoms and small molecules in standard form and nanometres, order-of-magnitude estimates, the symbols for much less than, much greater than and approximately, and density as mass per unit volume, its units and how it compares between objects. | 17 |
| Density of the states of matter, and density calculations | The particle arrangements in solids, liquids and gases and how they explain differences in density, why ice floats, rearranging density = mass ÷ volume for calculations, and measuring the density of regular and irregular solids and of liquids with a balance, callipers, eureka can and measuring cylinder. | 27 |
| Conservation of mass in changes of state | The names of the changes of state including sublimation, why mass is conserved when ice melts or a puddle evaporates, what a physical change is and how it differs from a chemical change, and why a change of state makes no new substance. | 16 |
| Heating a system, and specific heat capacity | The two effects of heating a system, internal energy and particle speed, why the temperature holds steady during a change of state, specific heat capacity and the specific latent heats of fusion and vaporisation with their units and when each is used, and the flat section of a cooling curve for stearic acid. | 17 |
| Calculations with specific heat capacity and latent heat | The relationship between energy, mass, specific heat capacity and temperature change, worked examples finding each quantity, the energy needed to change state, and a combined melting and warming calculation. | 29 |
| Gas molecules, temperature and pressure | How gas molecules move, what temperature and pressure mean in terms of molecules, what a closed system is, and why heating or cooling a sealed rigid container changes its pressure. | 16 |
| Compressing a gas, and changing its volume | What happens to a gas when the pressure on it rises or falls, why gases compress easily, how volume and pressure are linked at constant temperature, and why a crisp bag swells uphill. | 16 |
| Doing work on a gas | Why compressing a gas raises its temperature, why a bicycle pump barrel warms, which store gains energy, how molecules speed up against a moving piston, and why an expanding gas cools. | 8 |
| Atmospheric pressure and why it varies with height | What the atmosphere is, what causes its pressure, the uniform density assumption, why air does not escape, where pressure is greatest, and why pressure and density fall with height. | 16 |
| Floating, sinking and pressure in a liquid | Why objects float or sink according to their average density, upthrust and why a steel ship floats, why pressure in a liquid increases with depth and density and acts in all directions, how a pressure difference produces upthrust, and calculating liquid pressure from height, density and gravitational field strength. | 21 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
OCR GCSE Physics A, Higher tier Active Recall Guide
Every topic, not just this one. 1,584 questions with their answers.