In ECET 2026 Chemistry, questions from Environmental Chemistry are asked every year.
Understanding pollution and its types is important because it links chemistry with real-life environmental issues.
📘 Concept Notes – Environmental Pollution
🌎 What is Environmental Pollution?
Environmental Pollution refers to the undesirable changes in the environment that cause harm to living organisms and natural resources.
Definition:
The addition of contaminants (pollutants) into the environment (air, water, or soil) in such concentration that it becomes harmful.
Formula (general pollution measure):
If 
, pollution is present.
🌫️ Types of Environmental Pollution
1️⃣ Air Pollution
- Caused by gases, smoke, dust, and chemicals in the atmosphere.
- Major Pollutants: CO, CO₂, SO₂, NOₓ, particulate matter, CFCs.
- Sources: Vehicles, industries, burning of fossil fuels.
- Effects:
- Respiratory problems, acid rain, global warming, ozone depletion.
- Control Methods:
- Use of catalytic converters, plantation of trees, clean fuels, and green energy.
Example:
Smog formation in cities like Delhi due to vehicle emissions and industrial smoke.
2️⃣ Water Pollution
- Occurs when unwanted substances are added to water bodies.
- Major Pollutants: Detergents, sewage, heavy metals, pesticides, plastics.
- Sources: Domestic waste, industrial effluents, agricultural runoff.
- Effects:
- Affects aquatic life, causes diseases like cholera, eutrophication (excessive algae growth).
- Control Methods:
- Sewage treatment, waste recycling, reducing plastic usage.
Formula (Dissolved Oxygen – DO):
Low BOD → clean water
High BOD → polluted water
3️⃣ Soil Pollution
- Caused by addition of harmful chemicals to soil.
- Pollutants: Pesticides, fertilizers, plastics, and heavy metals.
- Effects:
- Reduces fertility, affects crop yield, contaminates groundwater.
- Control:
- Organic farming, minimizing chemical fertilizer use, and soil testing.
Example:
Use of DDT leading to soil contamination.
4️⃣ Noise Pollution
- Caused by unwanted loud sounds.
- Sources: Traffic, factories, loudspeakers, airplanes.
- Effects:
- Hearing loss, stress, hypertension.
- Control:
- Sound barriers, proper zoning, limiting loudspeakers.
Formula (Sound Level):
Where 
= intensity of sound, 
= reference intensity.
5️⃣ Thermal Pollution
- Caused by discharge of hot water from industries into water bodies.
- Effects:
- Reduces oxygen levels, affects aquatic life.
- Control:
- Cooling towers and recycling heated water.
6️⃣ Radioactive Pollution
- Caused by release of radioactive materials from nuclear plants or testing.
- Effects:
- Causes genetic mutations, cancer, and affects soil and water.
- Control:
- Safe disposal of radioactive waste, protective storage, and radiation monitoring.
🔟 10 Expected MCQs – ECET 2026
Q1. The most common cause of air pollution is:
A) Industrial gases
B) Forests
C) Ocean water
D) Dust storms
Q2. The gas responsible for acid rain is:
A) CO
B) SO₂
C) O₂
D) H₂
Q3. BOD stands for:
A) Biological Oxide Density
B) Biochemical Oxygen Demand
C) Basic Oxygen Data
D) Biological Oxygen Depth
Q4. High BOD value indicates:
A) Pure water
B) Less polluted water
C) Highly polluted water
D) Distilled water
Q5. Which of the following is a greenhouse gas?
A) CO₂
B) O₂
C) H₂
D) N₂
Q6. Main source of soil pollution is:
A) Fertilizers
B) Oxygen
C) Rainwater
D) Wind
Q7. The intensity of sound is measured in:
A) Joules
B) Decibels
C) Watts
D) Meters
Q8. Radiation pollution is caused by:
A) Water waste
B) Fertilizers
C) Nuclear waste
D) Dust
Q9. The best way to control air pollution is:
A) Cut trees
B) Use of green fuels
C) Use of more vehicles
D) Burn plastics
Q10. The harmful effect of thermal pollution is:
A) Increases aquatic life
B) Improves oxygen
C) Reduces aquatic life
D) Enhances water purity
✅ Answer Key
| Q.No | Answer |
|---|---|
| Q1 | A |
| Q2 | B |
| Q3 | B |
| Q4 | C |
| Q5 | A |
| Q6 | A |
| Q7 | B |
| Q8 | C |
| Q9 | B |
| Q10 | C |
🧠 Explanations
- Q1 → A: Industrial gases cause maximum air pollution.
- Q2 → B: Sulphur dioxide leads to acid rain.
- Q3 → B: BOD = Biochemical Oxygen Demand.
- Q4 → C: High BOD → high organic pollution.
- Q5 → A: Carbon dioxide is a greenhouse gas.
- Q6 → A: Chemical fertilizers pollute soil.
- Q7 → B: Sound level measured in decibels (dB).
- Q8 → C: Nuclear waste emits radiation.
- Q9 → B: Green fuels reduce harmful emissions.
- Q10 → C: Hot water kills aquatic organisms.
🎯 Why Practice Matters
Environmental Chemistry topics are scoring and conceptual.
Questions are usually theory-based or definition-type, making it easy to secure marks by understanding causes, effects, and control methods of each pollution type.
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