Question 1: Define density in your own words and state its SI unit.

Answer: Density is the mass of a substance per unit volume, measured in kilograms per cubic metre (kg/m^3).

Question 2: Explain why density is an important property in the particle model of matter.

Answer: Density helps determine whether materials will float or sink and provides insight into the arrangement and packing of particles within a substance.

Question 1: A metal block has a mass of 540 grams and a volume of 600 cm^3. Calculate its density in kg/m^3.

Answer: Density = (0.540 kg) / (0.0006 m^3) = 900 kg/m^3

Question 2: A plastic container has a mass of 250 grams and an internal volume of 5000 cm^3. What is its density?

Answer: Density = (0.250 kg) / (0.005 m^3) = 50 kg/m^3

Question 1: Describe a safe method to measure the volume of an irregular solid object using water displacement. List any safety precautions you should take.

Answer: Use a overflow container or a graduated cylinder filled with water. Carefully submerge the object without splashing and record the water level change. Avoid inhaling vapours or handling sharp objects to prevent injury.

Question 2: Identify two variables that must be controlled during a density experiment and explain why.

Answer: Variables such as temperature and measurement accuracy must be controlled because they can affect the density readings by changing the material's volume or mass.

Question 1: A piece of aluminium with a mass of 2.7 kg displaces 3.000 m^3 of water. Determine its density and compare it to the known density of aluminium (about 2700 kg/m^3). Is the sample pure aluminium?

Answer: Density = 2.7 kg / 3.000 m^3 = 900 kg/m^3. This is significantly lower than the known density of aluminium, indicating the sample may be mixed with other materials or not pure aluminium.

Question 1: Explain how the concept of density is used in the design of submarines and ships to ensure stability in water.

Answer: Submarines and ships are designed with specific densities by adjusting ballast and construction materials so that they have a density close to water. This allows them to control buoyancy, enabling them to sink or float safely and maintain stability in water.

Question 1: Describe how density is important in the petroleum industry, particularly in separating oil from water during refining.

Answer: Density allows the separation of oil from water because they have different densities. Oil, being less dense, floats on water, enabling easier extraction and refining.