NEET 2025 MCQ with Answer Explanation : “Environmental Issues”.

Here below some basic MCQ’s of Environmental Issues with Answer which is explained in details. Let’s check one by one.

1. Which of the following is the major cause of acid rain?
   A) Carbon dioxide
   B) Methane
   C) Sulfur dioxide
   D) Nitrogen gas

Answer: C) Sulfur dioxide

Explanation:
Acid rain is primarily caused by the emission of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) into the atmosphere. These gases react with water vapor in the atmosphere to form sulfuric acid (H₂SO₄) and nitric acid (HNO₃), which precipitate as acid rain. Carbon dioxide and methane contribute to global warming, but they do not directly cause acid rain.

2. Ozone depletion in the stratosphere is mainly caused by which of the following?
   A) Carbon dioxide
   B) Chlorofluorocarbons (CFCs)
   C) Sulfur dioxide
   D) Methane

Answer: B) Chlorofluorocarbons (CFCs)

Explanation:
CFCs are compounds that, when released into the atmosphere, break down under UV radiation, releasing chlorine atoms. These chlorine atoms react with ozone (O₃) in the stratosphere, leading to its depletion. This depletion reduces the protection offered by the ozone layer against harmful UV radiation.

3. Which of the following is an example of a primary pollutant?
   A) Ozone
   B) Sulfuric acid
   C) Carbon monoxide
   D) Peroxyacetyl nitrate (PAN)

Answer: C) Carbon monoxide

Explanation:
A primary pollutant is a pollutant emitted directly into the atmosphere from a source. Carbon monoxide (CO) is a primary pollutant as it is directly emitted from sources like motor vehicles and industrial processes. Ozone and PAN are secondary pollutants, formed by the reaction of primary pollutants in the atmosphere.

4. Which of the following best describes biomagnification?
   A) Increase in the population of species over time
   B) Increase in the concentration of toxins at higher trophic levels
   C) Decrease in biodiversity due to deforestation
   D) Increase in the number of trophic levels in a food chain

Answer: B) Increase in the concentration of toxins at higher trophic levels

Explanation:
Biomagnification refers to the process where the concentration of toxic substances, like pesticides or heavy metals, increases as they move up the food chain. Organisms at higher trophic levels tend to accumulate greater amounts of these toxins, which can have harmful effects.

5. Which of the following gases contributes most to global warming?
   A) Methane
   B) Carbon dioxide
   C) Nitrous oxide
   D) Ozone

Answer: B) Carbon dioxide

Explanation:
While methane, nitrous oxide, and ozone all contribute to global warming, carbon dioxide (CO₂) is the largest contributor due to its significant abundance and longer atmospheric lifetime. Human activities such as the burning of fossil fuels have greatly increased CO₂ levels in the atmosphere, leading to the enhanced greenhouse effect.

6. Which of the following is a consequence of eutrophication in water bodies?
   A) Increase in dissolved oxygen
   B) Reduction in fish population
   C) Decrease in algal growth
   D) Increase in water transparency

Answer: B) Reduction in fish population

Explanation:
Eutrophication occurs when excess nutrients, particularly nitrogen and phosphorus, enter water bodies, leading to excessive algal growth. When algae die and decompose, oxygen levels in the water drop (hypoxia), which can result in the death of fish and other aquatic organisms.

7. Which of the following practices is most effective in reducing soil erosion?
   A) Overgrazing
   B) Crop rotation
   C) Deforestation
   D) Urbanization

Answer: B) Crop rotation

Explanation:
Crop rotation helps in maintaining soil fertility and structure, which reduces soil erosion. Practices like overgrazing, deforestation, and urbanization lead to the loss of vegetation cover, making the soil more prone to erosion by wind and water.

8. The greenhouse effect is primarily due to which of the following gases?
   A) Nitrogen
   B) Oxygen
   C) Greenhouse gases like CO₂, CH₄, and N₂O
   D) Ozone

Answer: C) Greenhouse gases like CO₂, CH₄, and N₂O

Explanation:
The greenhouse effect is caused by the trapping of heat in the Earth’s atmosphere due to gases like carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). These gases allow sunlight to enter the atmosphere but trap the heat radiated from the Earth’s surface, contributing to global warming.

9. Which of the following is an example of a renewable energy source?
   A) Natural gas
   B) Coal
   C) Solar energy
   D) Petroleum

Answer: C) Solar energy

Explanation:
Solar energy is a renewable energy source because it is abundant and replenished naturally. Other options like natural gas, coal, and petroleum are fossil fuels, which are finite and take millions of years to form, making them non-renewable.

10. Which of the following best describes the concept of sustainable development?
    A) Development that meets the needs of the present without compromising the ability of future generations to meet their own needs
    B) Development focused solely on economic growth
    C) Development that maximizes the use of natural resources
    D) Development that prioritizes industrialization

Answer: A) Development that meets the needs of the present without compromising the ability of future generations to meet their own needs

Explanation:
Sustainable development emphasizes balancing economic growth, environmental protection, and social well-being. It ensures that resources are used responsibly so that future generations can enjoy the same quality of life as the present generation.