Question 1: Define the term 'state of matter' and describe the main differences between solids, liquids, and gases.

Answer: A state of matter refers to the physical form of a substance, determined by the arrangement and movement of its particles. Solids have fixed shapes and volumes with tightly packed particles; liquids have fixed volumes but take the shape of their container with particles that are close but can move past each other; gases have neither fixed shape nor volume with particles that are far apart and move freely.

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

Answer: Gases are highly compressible because their particles are far apart with lots of space between them, allowing them to be pushed closer together, unlike solids and liquids where particles are tightly packed.

Question 3: Describe the particle movement in a liquid compared to a solid.

Answer: In a liquid, particles are close together but can move past each other, allowing flow. In a solid, particles are fixed in a regular pattern and only vibrate in place.

Question 1: Calculate the volume occupied by 2 mol of a gas at standard temperature and pressure (STP). (Use the molar volume of 22.4 L per mol).

Answer: 44.8 litres

Question 2: A sample of a gas has a volume of 10 litres at 25°C and 1 atm pressure. If the temperature is increased to 50°C at constant pressure, what is the new volume? (Use Charles's Law: V1/T1 = V2/T2, temperatures in Kelvin).

Answer: 13.33 litres

Question 1: Describe a safe method to observe the melting of ice in a laboratory setting, including safety precautions.

Answer: Place the ice in a test tube or beaker on a heat-resistant surface, and gently warm using a water bath or a controlled heat source while wearing safety goggles and gloves. Ensure proper ventilation and avoid direct flame to prevent accidents.

Question 2: Identify two variables that could affect the rate at which a liquid evaporates and explain how they influence the process.

Answer: Temperature: Higher temperature increases evaporation rate by providing energy for particles to escape. Surface area: Larger surface area allows more particles to escape at once, increasing evaporation.

Question 1: A container of gas is compressed, and its pressure doubles while temperature remains constant. Explain what happens to the volume of the gas and why.

Answer: The volume of the gas decreases to half its original size because, according to Boyle's Law, pressure and volume are inversely proportional when temperature is constant.

Question 2: A student observes that a sealed balloon shrinks after being placed outside on a cold day. Explain the scientific reason for this observation.

Answer: The temperature decreases, causing the gas particles inside the balloon to lose energy and move less, which reduces the pressure and volume, making the balloon shrink.

Question 1: Describe how the arrangement and movement of particles differ between solids, liquids, and gases, and explain how these differences influence their physical properties.

Answer: In solids, particles are tightly packed in a fixed, regular arrangement and only vibrate in place, resulting in fixed shape and volume. In liquids, particles are close but can move past each other, allowing flow and conforming to the shape of their container. In gases, particles are far apart and move freely at high speeds, filling the entire volume of their container. These arrangements determine properties such as shape, volume, compressibility, and flow.

Question 2: A gas at a pressure of 1 atm and a temperature of 300 K occupies a volume of 20 litres. If the temperature is increased to 600 K at constant pressure, what will be the new volume? Use Charles's Law.

Answer: 40 litres

Question 1: Explain how understanding the properties of gases is important in the design of aeroplanes and their fuel systems.

Answer: Knowing how gases behave under different pressures and temperatures helps engineers design fuel systems that can operate efficiently at various altitudes and ensure safe pressure management within the aircraft.

Question 2: Discuss how the principles of states of matter are applied in the technology of refrigeration and air conditioning.

Answer: Refrigeration systems use the principles of gas compression and expansion, exploiting gas properties such as pressure and temperature changes to transfer heat and produce cooling.