Pollution (Air, Water, Soil) — Homi Bhabha Class 9 Biology MCQs with Solutions
Free Homi Bhabha Class 9 Biology Pollution (Air, Water, Soil) MCQs with step-by-step solutions (10 questions). Part of Ecosystem & Environmental Management. Practise online on Prepizo — no login needed.
▶ Practise Pollution (Air, Water, Soil) online (free)
Questions with solutions
Q1 — Pollution (Air, Water, Soil) · medium · theory
A major cause of air pollution in cities is the:
A. rainfall
B. burning of fossil fuels by vehicles and industries ✓ Correct
C. planting of trees
D. use of solar energy
Solution: Vehicles and industries release smoke and harmful gases, polluting the air.
Q2 — Pollution (Air, Water, Soil) · hard · theory
Acid rain is caused mainly by the release of ______ into the atmosphere:
A. sulphur dioxide and nitrogen oxides ✓ Correct
B. oxygen and nitrogen
C. water vapour
D. carbon dioxide only
Solution: SO₂ and NOₓ from burning fuels dissolve in rain to form acids, causing acid rain.
Q3 — Pollution (Air, Water, Soil) · medium · theory
Which of the following is a common water pollutant?
A. Untreated sewage and industrial waste ✓ Correct
B. Sunlight
C. Oxygen
D. Rain water
Solution: Sewage, industrial effluents and chemicals pollute water bodies.
Q4 — Pollution (Air, Water, Soil) · hard · theory
The excessive use of chemical pesticides and plastics mainly causes:
A. oxygen pollution
B. noise pollution
C. soil pollution ✓ Correct
D. sound pollution
Solution: Pesticides and non-degradable plastics accumulate in the soil, causing soil pollution.
Q5 — Pollution (Air, Water, Soil) · medium · theory
A poisonous gas released by the incomplete burning of fuels in vehicles is:
A. carbon monoxide ✓ Correct
B. oxygen
C. nitrogen
D. water vapour
Solution: Carbon monoxide (CO), formed in incomplete combustion, is a toxic air pollutant.
Q6 — Pollution (Air, Water, Soil) · hard · theory
Which practice would help REDUCE air pollution?
A. Using more diesel vehicles
B. Using public transport and clean energy ✓ Correct
C. Cutting down forests
D. Burning more coal
Solution: Public transport and clean (renewable) energy reduce the emission of pollutants.
Q7 — Pollution (Air, Water, Soil) · easy · theory
Which gas released from vehicle exhaust binds tightly with haemoglobin in blood and reduces the transport of oxygen?
A. Carbon monoxide ✓ Correct
B. Oxygen
C. Nitrogen
D. Carbon dioxide
Solution: Carbon monoxide (CO) combines with haemoglobin far more strongly than oxygen does, forming carboxyhaemoglobin and lowering the ability of blood to carry oxygen.
Q8 — Pollution (Air, Water, Soil) · medium · theory
Runoff of excess fertilizer into a lake causes a heavy growth of algae, after which many fish die. The main reason the fish die is:
A. Decomposition of the dead algae uses up dissolved oxygen, suffocating the fish ✓ Correct
B. Algae block sunlight and nothing else
C. Fertilizers directly poison the fish
D. The water suddenly becomes very acidic
Solution: This is eutrophication. When the algal bloom dies, decomposer bacteria multiply and consume dissolved oxygen while breaking it down, leaving too little oxygen for fish and other aquatic animals.
Q9 — Pollution (Air, Water, Soil) · medium · theory
A non-degradable pesticide such as DDT enters an aquatic food chain. In which organism will it be found in the highest concentration?
A. Large fish-eating birds ✓ Correct
B. The surrounding water
C. Small fish
D. Phytoplankton
Solution: Persistent pesticides undergo biomagnification: their concentration increases at each higher trophic level. The top consumer, the fish-eating bird, accumulates the greatest amount.
Q10 — Pollution (Air, Water, Soil) · hard · numerical
A pesticide is present in producers at 0.5 ppm and its concentration increases 10 times at each higher trophic level. What is its concentration in the third-level consumer (three levels above the producer)?
A. 1500 ppm
B. 50 ppm
C. 500 ppm ✓ Correct
D. 5 ppm
Solution: Multiply by 10 for each level up: producer 0.5, first consumer 5, second consumer 50, third consumer 500 ppm.