Enviromental Sciences MCQs - 2025

Unconfined aquifers are near the surface with no impermeable layer, allowing pollutants (e.g., pesticides) to seep in easily. Confined aquifers (C) are deeper and protected by rock layers.

Pakistan, after its 2022 floods, led demands for climate compensation at COP27 (2022).

Burning fossil fuels (coal, oil, gas) releases CO₂, the primary greenhouse gas. Planting trees (A) absorbs CO₂, and recycling (C) reduces waste but doesn’t directly lower emissions.

• The exact conversion of 100 ppb is 0.00001%

• None of the given options match

• Therefore, the correct answer is:

✅ (D) None of these

Bioaccumulation refers to toxins accumulating in living organisms (e.g., mercury in fish). Option (A) is a typo ("Organs" vs. "organisms").

NEQS are Pakistan’s regulatory limits for pollutants in air/water (e.g., industrial emissions).

• Stratopause: Stratosphere-Mesosphere boundary (~50 km altitude).

• Tropopause (B) separates Troposphere/Stratosphere.

• Thermopause (C) is the atmosphere’s outer layer.

Healthy plants reflect infrared light (detected by satellites like Landsat). UV (B) is used for ozone studies, and microwaves (C) for soil moisture.

Disaster risk = Probability (likelihood of hazard) × Vulnerability. Recovery (A) and preparedness (B) are mitigation steps, not core risk components.

COP28 was held in Dubai, UAE (November 2023). While Dubai is a city, it is the correct answer as the question refers to the host location. Option (D) is incorrect because a specific host was designated.

Biodiversity encompasses all living organisms (plants, animals, microbes) and their genetic diversity. An ecosystem (A) includes interactions between organisms and their environment, while biomass (B) is the total mass of living matter.

Biomagnification refers to pollutants (e.g., mercury, DDT) becoming more concentrated as they move up the food chain. Example: Small fish (low concentration) → Large fish (higher concentration) → Humans (highest concentration). Option (B) describes bioaccumulation, not biomagnification.

CFCs (used in refrigerants/aerosols) break down ozone molecules. CO₂ (B) causes global warming, not ozone depletion.

The UN defines <1,700 m³/year as water stress, <1,000 m³ as scarcity, and <500 m³ as absolute scarcity. The closest correct option is (B).

Incomplete burning of fuels produces toxic CO (due to insufficient oxygen). Methane (A) is a separate greenhouse gas.

Human actions (deforestation, pollution) drive species to extinction. Erosion (B) is soil loss; desertification (C) is land degradation to desert-like conditions.

EIA evaluates potential environmental effects of projects (e.g., dams, highways) before approval.

Conduction (heat transfer through direct contact) is negligible in the atmosphere because air is a poor conductor. Advection (A; horizontal movement) and convection (B; vertical circulation) dominate.

Groundwater dissolves minerals from surrounding rocks (e.g., limestone → high calcium). Precipitation (B) and temperature (C) affect recharge rates but not the chemical composition directly.

The tundra has permafrost (permanently frozen soil), temperatures below 0°C for most of the year, and only low-growing plants like mosses. Grasslands (A) have no permafrost, and rainforests (B) are warm and tree-rich.