Question 1: Define a solid, a liquid, and a gas in terms of particle arrangement and movement.

Answer: A solid has tightly packed particles in a fixed position; a liquid has particles close together but free to move; a gas has particles far apart and move independently.

Question 2: Explain why gases are highly compressible compared to solids and liquids.

Answer: Because gas particles are far apart with lots of space between them, they can be compressed into a smaller volume when pressure is applied.

Question 1: Calculate the density of a substance that has a mass of 150 grams and occupies a volume of 300 cm³. (Density = mass / volume)

Answer: 0.5 g/cm³

Question 2: A container holds 2 mol of a gas at a pressure of 101.3 kPa and a temperature of 273 K. Using the ideal gas law PV = nRT, calculate the volume of the gas in litres. (R = 8.314 J/mol·K)

Answer: 22.4 L

Question 1: Describe a simple experiment to observe the melting of ice and identify the variables involved. Include safety precautions.

Answer: Place ice in a beaker at room temperature and observe the change to water. Variables include temperature (independent), melting rate (dependent), and amount of ice (controlled). Safety precautions include handling ice with tongs and avoiding spills to prevent slips.

Question 1: A sample of gas shows an increase in pressure from 100 kPa to 150 kPa when the temperature increases from 273 K to 300 K at constant volume. Explain this observation using the kinetic particle model.

Answer: As temperature increases, gas particles gain kinetic energy and move faster, leading to more frequent and forceful collisions with container walls, which increases pressure.

Question 1: Discuss the differences in particle behaviour and properties between solids, liquids, and gases. Include examples and real-world applications. (6 marks)

Answer: Solids have tightly packed particles in fixed positions, resulting in definite shape and volume; for example, ice. Liquids have particles close together but free to move, giving indefinite shape but constant volume, like water. Gases have particles far apart and move freely, filling any container, such as oxygen. These differences influence properties like compressibility, flow, and diffusion, which are applied in industries like manufacturing and medicine.

Question 1: Explain how the principles of gas behaviour are utilised in the design of car airbags.

Answer: Car airbags use rapid inflation of gas (usually nitrogen) to cushion occupants during a collision. The gas expands quickly, filling the space and absorbing impact energy, based on gas laws related to pressure and volume.