Practise 16 real Federal Board questions on Environmental Chemistry from 2023 to 2026. See the answer and explanation as soon as you answer.
Environmental Chemistry is one of the 19 main chapters in our Federal Board FSC Chemistry question bank (11th and 12th class), and about 3% of its real questions come from it. Tayyari Karo has 16 real questions on this chapter from 2023 to 2026; 5 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 8 medium, 7 easy, 1 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
Chemical break down of organic compounds by microorganisms e.g., bacteria is called:
Answer: B. Respiration
Aerobic microbial respiration is the process by which bacteria break down organic matter, consuming dissolved oxygen — the basis of the BOD test.
Ozone is being mainly destroyed by:
Answer: A. CFC's
Chlorofluorocarbons (CFCs) release chlorine radicals in the stratosphere that catalytically destroy ozone molecules.
Which gas is mainly responsible for acid rain?
Answer: B. SO₂
SO₂ from fossil fuel combustion oxidizes and dissolves in atmospheric moisture to form sulfuric acid, the main cause of acid rain.
The formation of Ozone hole in stratosphere results in:
Answer: A. Exposure to UV radiation
The ozone layer normally absorbs harmful UV-B radiation; a hole in it lets more UV radiation reach the Earth's surface.
Chlorofluorocarbons play an effective role in removing O₃ in the:
Answer: A. Stratosphere
The ozone layer lies in the stratosphere; CFCs migrate there and catalytically destroy ozone.
Explain the role of NOx in the formation of Peroxyacetyl nitrate (PAN) with chemical reactions.
NOx (mainly NO₂) reacts with hydrocarbon-derived free radicals in the presence of sunlight (photochemical smog) — the peroxyacetyl radical (CH₃COOO•) formed from hydrocarbon oxidation reacts with NO₂: CH₃COOO• + NO₂ → CH₃COOONO₂ (PAN). NOx thus acts as a key reactant that combines with organic peroxy radicals to form PAN, a major component of photochemical smog and a powerful eye/lung irritant.
Write down any three measures that ensure the preservation of water resources.
1. Treating industrial and domestic wastewater before releasing it into rivers/lakes, to reduce pollution load.
2. Practicing water conservation methods (rainwater harvesting, efficient irrigation, avoiding wastage) to reduce excessive withdrawal from natural sources.
3. Controlling/regulating the use of fertilizers and pesticides near water bodies to prevent runoff contamination (eutrophication) of surface and ground water.
Explain green house effect and global warming as resulting in climate change.
Greenhouse effect: certain atmospheric gases (CO₂, CH₄, water vapor, N₂O, CFCs — 'greenhouse gases') allow incoming short-wavelength solar radiation to pass through and reach Earth's surface, but absorb and re-radiate the outgoing long-wavelength infrared radiation emitted by the warmed Earth, trapping heat within the atmosphere (analogous to a greenhouse's glass). This natural effect keeps Earth's average temperature warm enough to sustain life. …
The full model answer is in the app.
| Session | Questions |
|---|---|
| 2026 Annual | 2 |
| 2025 1st Annual | 6 |
| 2025 2nd Annual | 3 |
| 2024 Annual | 2 |
| 2023 Annual | 3 |
16 real Federal Board (FBISE) Chemistry questions on Environmental Chemistry from 2023 to 2026, for 11th and 12th class. Each one shows the session it came from.
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
You can start free with no signup. A small set of papers per subject is free, and Premium unlocks the full question bank.
