UGC NET — Environmental Sciences (subject code 89) · India · National Testing Agency for the University Grants Commission
Original practice questions written to the published syllabus · not past papersThe chemistry of water, soil and air that pollution, treatment and climate subjects assume: equilibria, the carbonate system, redox, gas solubility, ozone and smog chemistry. GATE ES Section 2 in full.
In the exams: GATE ES Section 2; UGC NET Environmental Sciences Unit 2; ICAR AIEEA-PG Physical Science Unit II (chemistry)
UGC NET Environmental Sciences — Unit 2 (environmental chemistry)
Fundamentals of environmental chemistry, chemical speciation, water and soil chemistry, atmospheric chemistry including photochemical smog, ozone depletion and acid rain, toxic chemicals, analytical techniques and radioactivity.
CUET-PG Environmental Sciences and CSIR-UGC NET (Earth, Atmospheric, Ocean and Planetary Sciences)
Carbonate chemistry and ocean acidification, atmospheric composition and ozone chemistry, and basic equilibrium and redox principles.
How our questions for UGC NET spread across the units of Environmental Chemistry. Difficulty: 1 easy, 20 medium, 17 hard.
| Stratospheric ozone chemistry and ozone-depleting substances | 7 | |
| Tropospheric ozone and photochemical smog | 6 | |
| Radioactivity and radionuclides in the environment | 6 | |
| Speciation of inorganic and organic contaminants | 5 | |
| Composition and structure of the atmosphere | 4 | |
| The carbonate system and ocean acidification | 3 | |
| Complexation, precipitation and solubility product | 2 | |
| Redox reactions, pe-pH diagrams and redox zonation | 2 | |
| Chemical bonding, concentration units, activity and ionic strength | 1 | |
| Solubility of gases in water: Henry's law | 1 | |
| Soil chemistry: organic matter, CEC, base saturation, SAR | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Which mercury species is most toxic and bioaccumulative, causing Minamata disease?
C. Methylmercury
Methylmercury biomagnifies in fish and caused Minamata disease in Japan in the 1950s.
Further reading: See the manual sources: Sawyer, McCarty & Parkin; Manahan; Stumm & Morgan; Seinfeld & Pandis; IS 10500; WMO/UNEP ozone assessment
What does a high log Kow (above about 5) indicate for an organic contaminant?
C. Hydrophobicity, sorption and bioaccumulation
High Kow compounds partition into lipids and organic carbon; they are poorly soluble and tend to bioaccumulate.
Further reading: See the manual sources: Sawyer, McCarty & Parkin; Manahan; Stumm & Morgan; Seinfeld & Pandis; IS 10500; WMO/UNEP ozone assessment
Why does high exchangeable sodium damage soil structure?
A. Sodium disperses clay particles, reducing aggregation, infiltration and aeration
Large hydrated Na⁺ ions expand the diffuse double layer, dispersing clay and sealing the soil surface.
Further reading: See the manual sources: Sawyer, McCarty & Parkin; Manahan; Stumm & Morgan; Seinfeld & Pandis; IS 10500; WMO/UNEP ozone assessment
Which radical is called the 'detergent of the atmosphere' because it initiates oxidation of most trace gases?
A. The hydroxyl radical (OH)
OH, formed from ozone photolysis and water vapour, oxidises methane, CO, VOCs, SO2 and NO2.
Further reading: See the manual sources: Sawyer, McCarty & Parkin; Manahan; Stumm & Morgan; Seinfeld & Pandis; IS 10500; WMO/UNEP ozone assessment
SO2 and NOx emissions cause acid deposition mainly by forming
B. sulphuric and nitric acids
Oxidation of SO2 and NOx produces H2SO4 and HNO3, the main acids in acid rain.
Further reading: See the manual sources: Sawyer, McCarty & Parkin; Manahan; Stumm & Morgan; Seinfeld & Pandis; IS 10500; WMO/UNEP ozone assessment
In a city centre where ozone formation is VOC-limited, what is the likely short-term effect of cutting NOx emissions alone?
D. Ozone rises as less NO titrates it
In NOx-rich (VOC-limited) regimes, NO removes ozone; reducing NOx can raise ozone, so VOC control is more effective there.
Further reading: See the manual sources: Sawyer, McCarty & Parkin; Manahan; Stumm & Morgan; Seinfeld & Pandis; IS 10500; WMO/UNEP ozone assessment
Why does the Antarctic ozone hole form mainly in spring?
D. Spring sun frees cloud-activated chlorine
Winter PSCs convert reservoirs to Cl2 and HOCl; spring sunlight releases Cl atoms that destroy ozone rapidly.
Further reading: See the manual sources: Sawyer, McCarty & Parkin; Manahan; Stumm & Morgan; Seinfeld & Pandis; IS 10500; WMO/UNEP ozone assessment
What did the Kigali Amendment (2016) to the Montreal Protocol add?
C. A phase-down of HFCs
HFCs do not deplete ozone but warm the climate; Kigali phases them down.
Further reading: See the manual sources: Sawyer, McCarty & Parkin; Manahan; Stumm & Morgan; Seinfeld & Pandis; IS 10500; WMO/UNEP ozone assessment
Which type of radiation is stopped by a sheet of paper but is most hazardous when inhaled or ingested?
A. Alpha particles
Alpha particles have low penetration but high ionisation; inside the body they damage tissue intensely.
Further reading: See the manual sources: Sawyer, McCarty & Parkin; Manahan; Stumm & Morgan; Seinfeld & Pandis; IS 10500; WMO/UNEP ozone assessment
Which radionuclide from nuclear accidents concentrates in the thyroid gland?
D. Iodine-131
I-131 (t½ ≈ 8 days) accumulates in the thyroid; Cs-137 behaves like potassium and Sr-90 like calcium.
Further reading: See the manual sources: Sawyer, McCarty & Parkin; Manahan; Stumm & Morgan; Seinfeld & Pandis; IS 10500; WMO/UNEP ozone assessment
Ten here, 38 in the app. The Laisha app has every practice question we have written to UGC NET in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
Free for ten days, then one subscription of US$10 a month. We would rather say so here than have you find it later.
An AI operating system for agriculture: free guides, manuals and tools written for every country.