Explanation

• A composite liner acts as a barrier that reduces the movement of contaminated liquid into the surrounding soil and groundwater.
• A leachate collection system collects polluted liquid produced when water passes through waste, allowing it to be treated safely.
• Methane capture collects gas released during the decomposition of biodegradable waste.
• Methane is a powerful greenhouse gas that contributes to global warming.
• Captured methane can be flared or used to generate energy, reducing its direct release into the atmosphere.

Last verified on 21-10-2026

Explanation

• Arsenic is a toxic substance that can contaminate groundwater and cause serious health problems after prolonged exposure.
• Water sources confirmed to have excessive arsenic should be clearly marked, and people should be advised not to use them for drinking or cooking.

Last verified on 21-10-2026

Explanation

• Nitrogen (N₂) makes up about 78% of Earth's atmosphere. 
• It is generally not considered an air pollutant in its normal form.

Additional information:

• Hydrocarbons can contribute to air pollution by reacting with nitrogen oxides to form ground-level ozone.
• Chromium, especially certain compounds such as hexavalent chromium, can pollute the air and pose serious health risks.
• Carbon dioxide (CO₂) is a greenhouse gas that contributes to global warming and is also classified as an air pollutant in some environmental frameworks.

Last verified on 21-10-2026

Explanation

• GIS (Geographic Information System) is a computer-based system used to collect, store, analyze, and display geographically referenced data.
• Its basic output is often a map that presents spatial information visually.
• GIS maps can show roads, buildings, rivers, land use, population distribution, and service locations.
• GIS also produces tables, statistics, reports, and spatial measurements, depending on the analysis.

Last verified on 21-10-2026

Explanation

• Hepatitis A vaccination provides effective protection against the Hepatitis A virus.
• Hepatitis A mainly spreads through contaminated food or water and the fecal–oral route.
• Washing hands thoroughly with soap and clean water, especially after using the toilet and before preparing or eating food, helps prevent infection.
• Drinking safe water and eating properly prepared food further reduce the risk of transmission.

Last verified on 21-10-2026

Explanation

• An endemic is the constant or usual presence of a disease in a particular area or population.
• An epidemic occurs when disease cases rise above the expected level within a specific region or population.
• A pandemic is an epidemic that spreads across multiple countries or continents, often affecting large numbers of people.
• Option 3 is incorrect because a pandemic is a global epidemic, not a global endemic.

Last verified on 21-10-2026

Explanation

• Bacteria are single-celled living organisms.
• Many can survive and reproduce independently under suitable conditions.
• Viruses contain genetic material (DNA or RNA) surrounded by a protein coat.
• They cannot reproduce independently and require a living host cell.
• Bacteria reproduce mainly through binary fission, in which one cell divides into two cells.
• Viruses multiply by entering host cells and using the cells’ machinery to produce new viruses.

Last verified on 21-10-2026

Explanation

• The lightning conductor or rod used for protecting buildings from lightning is made of copper.
• A lightning conductor is a metal rod installed at the highest point of a building to provide a safe path for lightning current to reach the ground.
• Copper is commonly used.
• Because it is an excellent electrical conductor.
• It has good resistance to corrosion.

Additional information:

• Light rod was invented by Benjamin Franklin in the 18th century.

Last verified on 21-10-2026

Explanation

• Australia is located in the Southern Hemisphere, where summer begins around December.
• During December, the Southern Hemisphere tilts towards the Sun because of Earth’s axial tilt of approximately 23.5°.

Additional information:

• Australia’s summer generally lasts from December to February, while winter lasts from June to August.

Last verified on 21-10-2026

Explanation

• A planet must orbit the Sun, have enough gravity to become nearly round, and clear most other objects from its orbital neighbourhood.
• In 2006, the International Astronomical Union (IAU) reclassified Pluto as a dwarf planet.

Additional information:

• The eight recognized planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Last verified on 21-10-2026