Question 1: Define density in terms of particles and explain its significance in the particle model.

Answer: Density is the mass of particles in a given volume. It indicates how tightly particles are packed, affecting an object's buoyancy and stability.

Question 2: What is the SI unit of density?

Answer: Kilogram per cubic metre (kg/m³)

Question 1: A block of aluminium has a mass of 540 grams and a volume of 600 cm³. Calculate its density in kg/m³. (Use the formula: Density = Mass / Volume).

Answer: Density = 900 kg/m³

Question 2: A sample of sulphur has a mass of 12 grams and a volume of 8 cm³. What is its density in g/cm³?

Answer: Density = 1.5 g/cm³

Question 1: Describe a simple experiment to measure the density of a solid object. Include the variables you would control, measure, and how you would ensure safety.

Answer: To measure the density of a solid, use a balance to find its mass and a displacement method with water to find its volume. Control variables include temperature and water cleanliness. Measure mass using a digital balance and volume by observing water displacement. Safety precautions include handling water carefully to avoid spills and ensuring the balance is stable.

Question 1: A scientist measures the mass and volume of three different substances, recording the following data: Substance A: Mass = 24 g, Volume = 12 cm³ Substance B: Mass = 50 g, Volume = 25 cm³ Substance C: Mass = 80 g, Volume = 40 cm³ Analyse this data to determine which substance is the densest.

Answer: Substance C is the densest, with a density of 2.0 g/cm³, compared to 2.0 g/cm³ for A and 2.0 g/cm³ for B (all have the same density).

Question 1: Explain how understanding the density of materials can help in designing boats that are safe and stable.

Answer: Knowing the density helps engineers choose materials with appropriate densities to ensure boats are buoyant and stable, preventing sinking or capsizing.

Question 2: In the manufacturing of lightweight alloys, why is it important to control the density of the material?

Answer: Controlling density ensures the alloy has the desired weight and strength, which is crucial for applications like aerospace where weight reduction is important.