Question 1: Define density and explain why it is important in environmental science.

Answer: Density is the mass per unit volume of a substance, typically measured in kg/m³. It is important in environmental science for identifying materials, assessing pollutant dispersion, and analysing ecological impacts.

Question 2: Describe the mechanism by which density can influence the environmental distribution of pollutants in water bodies.

Answer: Denser pollutants tend to sink and accumulate at the bottom, while less dense pollutants float, affecting their dispersal, accumulation, and potential ecological impact.

Question 1: A sample of soil has a mass of 1500 grams and occupies a volume of 0.75 m³. Calculate its density in kg/m³.

Answer: 2000 kg/m³

Question 2: A water sample has a mass of 2.5 kg and a volume of 2 litres. What is its density in kg/m³? (Note: 1 litre = 0.001 m³)

Answer: 1250 kg/m³

Question 1: Outline a basic procedure to measure the density of a sample of aluminium debris collected from a polluted riverbed.

Answer: Weigh the aluminium debris using a balance, measure its volume by submerging it in a graduated displacement container filled with water, and then calculate density using the formula: density = mass / volume.

Question 2: Identify two variables that must be controlled to ensure accurate density measurements in this experiment and explain why.

Answer: Variables include temperature (to prevent thermal expansion affecting volume measurements) and water purity (to avoid buoyancy errors).

Question 3: Suggest two safety precautions when handling environmental samples during the practical.

Answer: Wear gloves and eye protection to avoid contact with potentially hazardous materials; handle samples with care to prevent spills and contamination.

Question 1: A pollutant sample from a river has a measured density significantly higher than water. What does this imply about its behaviour in the water column?

Answer: It implies the pollutant is denser than water and is likely to sink, potentially accumulating at the riverbed.

Question 2: A collection of plastic debris in the ocean has a lower density than seawater. What environmental impact could this have?

Answer: The plastic debris would tend to float, spreading across the surface and affecting marine ecosystems and navigation.

Question 1: Describe how density measurements of pollutants can be used to assess the environmental impact of a chemical spill. Include considerations of practical methods, data interpretation, and ecological implications.

Answer: Density measurements help determine whether pollutants sink or float, influencing their dispersal and ecological impact. Practically, samples are collected and weighed, their volume measured via displacement, and density calculated. High-density pollutants tend to settle, potentially harming benthic organisms, while low-density pollutants may spread over large areas, affecting surface ecosystems. Interpreting these data allows environmental agencies to assess contamination severity and plan remediation strategies accordingly.

Question 1: Explain how density measurements are utilised in the design of biodegradable materials to reduce environmental pollution.

Answer: Designers measure and compare the densities of biodegradable materials to ensure they can effectively disintegrate in environmental conditions, reducing pollution and preventing accumulation in ecosystems.

Question 2: Discuss the importance of accurate density measurements in assessing the environmental safety of new chemical products.

Answer: Accurate density measurements help predict how chemicals will behave in the environment, such as whether they will sink, float, or disperse, aiding in safety assessments and regulatory compliance.