15 extra multiple-choice questions for Environmental Issues (12th Standard Zoology, Samacheer Kalvi), beyond the ones printed in the textbook — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
Which of the following is classified as a slowly degradable or persistent pollutant that remains unchanged in the environment for decades?
- A. Domestic sewage
- B. Vegetable waste
- C. DDTCorrect
- D. Mercury
Explanation. DDT takes decades or longer to degrade and is classified as a slowly degradable or persistent pollutant, unlike rapidly degradable organic wastes.
Q2
Which mobile application provides hourly updates on the National Air Quality Index (AQI) published by the Central Pollution Control Board (CPCB)?
- A. SameerCorrect
- B. Sameep
- C. Swachh
- D. Vayu
Explanation. The mobile app named 'Sameer' provides hourly updates to the public on the National Air Quality Index (AQI) as published by the CPCB.
Q3
What are the components of the acidic precipitation commonly known as acid rain?
- A. Hydrochloric acid and carbonic acid
- B. Sulphuric acid and nitric acidCorrect
- C. Phosphoric acid and acetic acid
- D. Citric acid and lactic acid
Explanation. Acid rain is a form of precipitation that contains acidic components, specifically sulphuric acid or nitric acid, which damage vegetation and aquatic ecosystems.
Q4
In which year was the National River Conservation Plan (NRCP) enacted to improve the water quality of major fresh water resources in India?
- A. 1974
- B. 1986
- C. 1995Correct
- D. 2000
Explanation. The National River Conservation Plan (NRCP) was enacted in the year 1995 to intercept, divert, and treat raw sewage flowing into Indian rivers.
Q5
According to the Noise Pollution (Regulation and Control) Rules, 2000, what is the permissible limit of noise in areas categorized as commercial during the day?
- A. 55 dB
- B. 65 dBCorrect
- C. 75 dB
- D. 120 dB
Explanation. Under the Noise Pollution Rules of 2000, the daytime permissible noise limit in areas categorized as commercial is 65 decibels.
Q6
In an aquatic food chain exhibiting biomagnification of DDT, if the water contains 0.003 ppb of DDT, what is the typical concentration found in fish-eating birds?
- A. 0.04 ppm
- B. 0.5 ppm
- C. 2 ppm
- D. 25 ppmCorrect
Explanation. Due to biomagnification, non-degradable DDT accumulates at successive trophic levels, increasing from 0.003 ppb in water to 25 ppm in top predators like fish-eating birds.
Q7
What is the name of the cold, clear, and nutrient-poor initial stage of a lake's natural aging process?
- A. Oligotrophic stageCorrect
- B. Mesotrophic stage
- C. Eutrophic stage
- D. Senescent stage
Explanation. A newly formed lake is cold, clear, and supports very little life due to low nutrient levels, which is called the oligotrophic stage.
Q8
Which gas is produced in anaerobic sludge digesters during the treatment of sewage and forms a key component of biogas?
- A. Nitrogen dioxide
- B. MethaneCorrect
- C. Oxygen
- D. Chlorofluorocarbon
Explanation. Anaerobic bacteria in sewage treatment digest the flocs and produce a mixture of gases including methane, carbon dioxide, and hydrogen sulphide, which make up biogas.
Q9
Which decentralized wastewater recycling system has been experimented with at Auroville in South India to recycle wastewater naturally?
- A. RZWT
- B. DEWATSCorrect
- C. NRCP
- D. CPCB
Explanation. Auroville has been experimenting with natural wastewater recycling using the DEWATS (Decentralized Wastewater Treatment System), while RZWT is used at Aravind Eye Hospital.
Q10
The celebrated agricultural scientist and environmental activist G. Nammalvar founded Vaanagam, also known as the Global Food Security Trust, at which district in Tamil Nadu?
- A. Pudukottai
- B. KarurCorrect
- C. Chennai
- D. Coimbatore
Explanation. G. Nammalvar, a pioneer of ecological and organic farming in Tamil Nadu, founded the Nammalvar Ecological Foundation (Vaanagam) in Karur district.
Q11
For which scientific research did the Indian soil biologist Dr. Sultan Ahmed Ismail receive a Doctor of Science (D.Sc.) degree from the University of Madras?
- A. Photochemical smog secondary pollutants
- B. Radioactive waste vitrification in dry cement caskets
- C. Role of earthworms in soil ecology and waste managementCorrect
- D. Biomagnification of heavy metals in food chains
Explanation. Dr. Sultan Ahmed Ismail was awarded a D.Sc. in Zoology for his pioneering research on the ecological role of earthworms in vermicomposting and waste management.
Q12
Which method of radioactive waste management involves encasing long-lived nuclear waste in dry cement caskets to prevent reaction and degradation?
- A. Delay and decay
- B. VitrificationCorrect
- C. Source segregation
- D. Dilute and disperse
Explanation. Vitrification is a method used to stabilize and prevent the reaction or degradation of radioactive waste by encasing it in dry cement caskets.
Q13
In personal computers, which toxic metal is most commonly associated with the cathode ray tube (CRT) and soldering compounds?
- A. LeadCorrect
- B. Mercury
- C. Cobalt
- D. Cadmium
Explanation. E-waste from computers contains hazardous materials, specifically lead in cathode ray tubes and soldering joints, while mercury is found in switches.
Q14
Which secondary pollutant is found in photochemical smog, is thermally unstable, and decomposes to cause severe eye irritation?
- A. Carbon monoxide
- B. Peroxyacetyl nitrateCorrect
- C. Sulphur dioxide
- D. Methyl guanosine
Explanation. Peroxyacetyl nitrate (PAN) is a secondary pollutant in photochemical smog that decomposes into radicals, causing irritation in human eyes.
Q15
Which eco-friendly toilet design is used in parts of India and Sri Lanka to recycle nutrients from human excreta to create fertilizer for agriculture?
- A. DEWATS
- B. RZWT
- C. EcoSanCorrect
- D. Sameer
Explanation. EcoSan (ecological sanitation) toilets are dry, eco-friendly systems that safely recycle nutrients from human excreta to benefit sustainable agriculture.
