Course Description


This course is targeted at Singapore Cambridge GCE O level students, but is also relevant to IGCSE students and Singapore's Integrated program students.

Solids, liquids and gases couldn't be more different. Or could they? It turns out there's something that everything we can see and touch has in common - they're made up of tiny particles, and it's the behaviour of these particles that determines their characteristics. So if you've ever wondered what happens when solid ice melts to form liquid water, maybe it's a good idea to check on what these small particles are doing...

Course Content

You will learn:

  • What happens to the structure of a substance when it melts, freezes, boils or condenses
  • Where pressure comes from
  • How to make a balloon shrink without having to touch it
  • How an odor spreads through a room

A link to the full O level Physics syllabus can be found here

Course Prerequisites

You will need to know:

  • That everything around us is made up of really really small particles
  • How to watch videos on your computer

Math Arena

The instructor is from Math Arena.The instructor is absolutely passionate about teaching and you'll find the lessons engaging and ultimately rewarding.

Course curriculum

  • 1


    • Subject Content Requirements

  • 2

    Basics of the model

    • Q1 The model

    • Q2 Gas behaviours 1

    • Q3 Gas behaviours 2

    • Q4 Liquids according to the model

    • Q5 Changes of state according to the model

    • Q6 When ice melts to become water, which force must be overcome?

    • Q7 Shape and volume of solids

    • Q8 Density and compressibility

  • 3

    More on the structure of solids, liquids and gases

    • Q9 What is a property of both liquids and gases?

    • Q10 Assuming the temperature remains constant, which combination correctly describes the volume and the shape of a gas or liquid?

    • Q11 Which line in the table describes the properties of solids and of liquids at a fixed temperature?

    • Q12 A student has three sealed thin plastic bags. One bag is full of gas, one of liquid and one of solid. The student squeezes each bag to see if it changes shape, and warms each bag to see if it expands. Which bag contains gas?

  • 4

    Evaporation and boiling

    • Q13 As the atmospheric pressure on the surface of a liquid decreases, its boiling point

    • Q14 A beaker of liquid is placed under a bell jar. The pressure of the air above the liquid is reduced and some of the liquid evaporates. This causes the liquid to become colder.

    • Q15 Water spilled on the ground on a hot day evaporates. Which diagram represents the change in arrangement of the particles in the water as it evaporates?

    • Q16 The diagram shows a cross-section through a rain-water puddle formed in a shallow hole in a road surface.

    • Q17 What happens when liquid is being heated at its boiling point?

  • 5

    Heat and particles

    • Q18 A substance consists of particles that are close together and moving past each other at random. The average speed of the particles is gradually increasing. What best describes the substance?

    • Q19 A sealed container filled with gas is plunged into cold water. Which one of the following best describes the changes which the gas and its molecules undergo during this process?

  • 6

    Changes in pressure, volume and temperature

    • Q27 The pressure of a fixed mass of gas in a cylinder is measured. The volume of the gas in the cylinder is then slowly decreased. Which graph could show the change of pressure of the gas during this process?

    • Q20 If the temperature of a fixed quantity and volume of gas changes, what also changes?

    • Q20 explanation - Ideal Gas Law

    • Q21 To study the relationship between the temperature and volume of a gas, which factor must be held constant?

    • Q22 Suppose the temperature of the air in a balloon is increased. If the pressure remains constant, what quantity must change?

    • Q23 The gas pressure inside a container decreases when

    • Q24 A piston traps a certain mass of gas inside a cylinder. Initially the piston is halfway along the length of the cylinder. The piston is now moved towards the open end of the cylinder. The temperature of the gas remains constant.

    • Q25 A partially inflated balloon is placed under a bell jar. A vacuum pump (air pump) is turn on for several minutes and the volume of the balloon increases. Which pressure changes occur within the bell jar and within the balloon?

    • Q26 Bubbles of gas, escaping from the mud at the bottom of a deep lake, rise to the surface. As the bubbles rise to get larger, why is this?

    • Q27 The pressure of a fixed mass of gas in a cylinder is measured. The volume of the gas in the cylinder is then slowly decreased. Which graph could show the change of pressure of the gas during this process?

  • 7

    Calculations on changing pressure and volume

    • Q28 A gas is trapped inside a cylinder by a movable piston. The piston is pulled out a distance of 30cm, so that the length of the gas column is now 50cm. The temperature of the gas does not change. What is the new pressure of the gas?

    • Q29 Water of depth 10 m exerts a pressure equal to atmospheric pressure. An air bubble rises to the surface of a lake. When the bubble reaches the surface, its volume is 6 cm3. What was the volume of the air bubble at the bottom of the lake?

  • 8

    Particle bombardment

    • Q30 Why does a can collapse when a vacuum pump removes air from the can?

    • Q31 An explosion can occur if an aerosol can is left in direct sunlight. What causes the explosion?

    • Q32 A fixed mass of gas is heated while kept at constant volume. How do the properties of the molecules of the gas change?

    • Q34 Driving a car raises the temperature of the tyres. This causes the pressure of the air in the tyres to increases. Why is this?

    • Q35 The pressure of a gas in the cylinder is the same at all points in the cylinder. Which states explains this?

    • Q36 A balloon is squeezed and the pressure of the air inside increases. If there is no change in the temperature of the air, the molecules of air caused this increase in pressure, because they

    • Q33 A balloon is inflated in a cold room. When the room becomes much warmer, the balloon becomes larger. How does the behaviour of the air molecules in the balloon explain this?

    • Q37 The pressure of a gas is doubled when its volume is halved and the temperature is unchanged. Which of the following statements correctly explain(s) the effect above?

  • 9

    Brownian motion

    • Q38 Two gases with unequal masses are injected into opposite ends of a long tube at the same time and allowed to diffuse toward the center. They should begin to mix

    • Q39 Brownian motion shows that

    • Q40 In a Brownian motion experiment, heavy smoke particles settle quickly but very small smoke particles remain suspended for long periods of time. Which one of the following statements explains why the small smoke particles do not settle?

    • Q41 When the Brownian motion of smoke particles in air is observed with a microscope, moving points of light are seen. These points of light are reflections from

    • Q42 The diagram shows a small glass box containing some air and smoke. A microscope is used to observe the smoke.

    • Q43 Smoke particles trapped in an illuminated as cell are observed under a microscope. The movement of one particle is shown in the diagram. What can be deduced from this random motion?

  • 10

    Structured Questions

    • SQ1 How gases exert pressure

    • SQ2 Why pressure increases with decreased volume

    • SQ3 Why pressure increases with increased temperature

    • SQ4 Why volume increases with temperature

    • SQ5 Why are metals such good conductors of heat?

    • SQ6 Why does hot air rise?

    • SQ7 Brownian motion