Every Book Back multiple-choice question from Environmental Issues (12th Standard Zoology, Samacheer Kalvi) — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
Right to Clean Water is a fundamental right, under the Indian Constitution
- A. Article 12
- B. Article 21Correct
- C. Article 31
- D. Article 41
Explanation. Under Article 21 of the Indian Constitution, the right to life has been judicially interpreted to include the right to clean water as a fundamental requirement for human survival and dignity.
Q2
The 'thickness' of Stratospheric Ozone layer is measured in/on:
- A. Sieverts units
- B. Dobson unitsCorrect
- C. Melson units
- D. Beaufort Scale
Explanation. Dobson units are the standard scientific unit used to measure the total amount or thickness of ozone in the stratospheric column overhead, with one unit representing a layer of 0.01 mm at standard temperature and pressure.
Q3
As per 2017 statistics, the highest per capita emitter of Carbon dioxide in the world is
- A. USA
- B. China
- C. QatarCorrect
- D. Saudi Arabia
Explanation. Based on global statistics, Qatar has the highest per capita carbon dioxide emissions due to its small population and highly energy-intensive industrial processes, particularly in liquified natural gas production and water desalination.
Q4
The use of microorganism metabolism to remove pollutants such as oil spills in the water bodies is known as
- A. Biomagnification
- B. BioremediationCorrect
- C. Biomethanation
- D. Bioreduction
Explanation. Bioremediation is an eco-friendly technology that utilizes the natural metabolic processes of microorganisms, such as bacteria and fungi, to degrade and remove environmental contaminants like oil spills from aquatic ecosystems.
Q5
Which among the following always decreases in a Food chain across tropic levels?
- A. Number
- B. Accumulated chemicals
- C. EnergyCorrect
- D. Force
Explanation. In accordance with the ten percent law of energy transfer, energy is lost as metabolic heat at each successive trophic level in a food chain, resulting in a continuous decrease in available energy at higher levels.
Q6
In the E-waste generated by the Mobile Phones, which among the following metal is most abundant?
- A. CopperCorrect
- B. Silver
- C. Palladium
- D. Gold
Explanation. In electronic waste generated from discarded mobile phones, copper is the most abundant metal because of its extensive use in printed circuit boards, wiring, and electrical connectors.
Q7
___________ is/are an ideal disinfectant for waste water.
- A. U-V Rays
- B. Chlorination
- C. Boiling
- D. OzonisationCorrect
Explanation. Ozonisation is considered an exceptionally effective and ideal method for disinfecting wastewater as ozone is a powerful oxidant that destroys pathogens and inactivates chlorine-resistant microorganisms without leaving harmful chemical residues.
Q8
SMOG is derived from :
- A. Smoke
- B. Fog
- C. Both A and BCorrect
- D. Only A
Explanation. Smog is a form of air pollution created by the combination of smoke and fog in the atmosphere, often aggravated by industrial emissions and vehicular exhaust under specific weather conditions.
Q9
Excess of fluoride in drinking water causes:
- A. Lung disease
- B. Intestinal infection
- C. FluorosisCorrect
- D. None of the above
Explanation. Consuming drinking water with excessively high concentrations of fluoride leads to fluorosis, a condition characterized by the mottling of teeth, damage to tooth enamel, and in severe cases, skeletal complications.
About these Environmental Issues questions
These are the Book Back multiple-choice questions for Environmental Issues from the Tamil Nadu State Board (Samacheer Kalvi) 12th Standard Zoology syllabus. Each question shows the correct option and an original, step-by-step explanation so you understand the method, not just the answer. Use the answer key above to jump to any question, then take the practice test to check yourself under exam-like conditions.
Frequently asked questions
How many MCQs are there in Environmental Issues?
This chapter has 9 book-back multiple-choice questions, each with the correct answer and a step-by-step explanation.
Are these 12th Standard Zoology MCQs free to practise online?
Yes. Every question, answer and explanation here is free, and you can also take them as a timed practice test.
Where can I find the Environmental Issues book-back answers?
The correct option for each question is highlighted on this page with a worked explanation, plus a quick answer-key summary at the top.
