Environment and Sustainable Development Class 12: Notes and Solved Questions

What Environment and Sustainable Development is about

Weightage: This chapter is part of Unit 7, Current Challenges facing Indian Economy (Part B Indian Economic Development), which carries 20 of the 80 theory marks together with the chapters Human Capital Formation in India; Rural Development; and Employment: Growth, Informalisation and Other Issues.Source: CBSE Economics (030) syllabus 2026-27, Unit 7 Current Challenges facing Indian Economy

In real board papers: asked in 2 of the 2 board papers we hold (2026 to 2026), on average 3.5 marks per paper. See the questions

Key concepts

Environment and its functions

NCERT section 7.2

Environment = the totality of all resources: biotic elements (birds, animals, plants, forests, fisheries) and abiotic elements (air, water, land, rocks, sunlight).

Four functions:

• Supplies resources: renewable resources can be used without exhaustion if used carefully (trees, fish); non-renewable resources are exhausted with use (fossil fuels).
• Assimilates waste.
• Sustains life by providing genetic and biodiversity.
• Provides aesthetic services such as scenery.

Worked example

Suppose a river supplies water for irrigation, carries away a town's treated sewage, supports fish and attracts tourists. Match each use to a function of the environment. [2 marks]

Try it first, then show the solutionSolution

1. Irrigation water: supplies resources.
2. Carrying sewage: assimilates waste.
3. Supporting fish: sustains life (biodiversity).
4. Tourism: aesthetic services.

Answer: All four functions are shown.

Carrying capacity, absorptive capacity and environmental crisis

NCERT section 7.2

Carrying capacity: the environment can perform its functions only if (i) resources are extracted no faster than they regenerate and (ii) wastes are within its absorptive capacity (its ability to absorb degradation). When these limits are crossed, the environment fails to sustain life: an environmental crisis.

Why problems are new: earlier, with a smaller population and before industrialisation, the supply of environmental resources and services exceeded demand. With population explosion and the industrial revolution, demand outran regeneration and absorptive capacity: a reversal of the supply-demand relationship for environmental quality.

Costs: polluted and dried-up rivers make water an economic good; exhausted resources force spending on research for new ones; poor air and water quality (NCERT: seventy per cent of India's water is polluted) raise respiratory and water-borne diseases and health spending; global problems raise government commitments. The opportunity costs of environmental damage are high.

Worked example

Suppose a lake holds 1,000 tonnes of fish that regenerate at 10% a year, and fishermen catch 150 tonnes a year. Is this sustainable? Show the stock for three years. [3 marks]

Try it first, then show the solutionSolution

1. Sustainable catch = regeneration = 100 tonnes a year.
2. Fish stock with a catch of 150 tonnes a year and 10% regeneration (tonnes)

   Year	Opening stock	Regeneration	Catch	Closing stock
   Year 1	1,000	100	150	950
   Year 2	950	95	150	895
   Year 3	895	89.50	150	834.50

3. The stock shrinks every year because extraction exceeds regeneration: carrying capacity is exceeded.

Answer: Not sustainable; the stock falls to 834.5 tonnes in three years.

Global warming

NCERT section Box 7.1

Global warming means the slow rise in the mean temperature of the air near the earth's surface, caused by more greenhouse gases since the Industrial Revolution, largely human-induced through burning fossil fuels and deforestation.

NCERT figures: atmospheric concentrations of carbon dioxide and methane have risen by 31% and 149% above pre-industrial levels since 1750; over the past century the temperature rose by 0.6°C and sea level by several inches.

Causes: burning coal and petroleum (carbon dioxide, methane, nitrous oxide, ozone), deforestation, methane from animal waste, and increased cattle production.

Effects: melting polar ice, rising sea level and coastal flooding; disruption of drinking water from snow melt; extinction of species; more frequent tropical storms; more tropical diseases.

The Kyoto conference (1997) produced an international agreement calling on industrialised nations to cut greenhouse gas emissions.

Worked example

Explain how deforestation contributes to global warming. [1 mark]

Try it first, then show the solutionSolution

1. Trees absorb carbon dioxide.
2. Cutting them both removes this sink and adds carbon dioxide to the atmosphere.

Answer: It increases atmospheric carbon dioxide, a greenhouse gas.

Ozone depletion

NCERT section Box 7.2

Ozone depletion is the reduction of ozone in the stratosphere, caused by high levels of chlorine and bromine compounds from chlorofluorocarbons (CFCs) (used in air-conditioners, refrigerators and aerosol propellants) and halons (used in fire extinguishers). With less ozone, more ultraviolet radiation reaches the earth, linked to skin cancer, lower phytoplankton production (affecting aquatic life) and effects on plant growth. NCERT notes a reduction of about 5% in the ozone layer from 1979 to 1990. The Montreal Protocol banned CFCs and other ozone-depleting chemicals.

Worked example

Why did countries agree to ban CFCs under the Montreal Protocol? [3 marks]

Try it first, then show the solutionSolution

1. CFCs release chlorine that destroys stratospheric ozone.
2. Less ozone lets more harmful UV radiation through.
3. UV causes skin cancer and harms aquatic and plant life.

Answer: To protect the ozone layer and prevent UV damage to health and ecosystems.

State of India's environment

NCERT section 7.3

Rich endowment: fertile soils (black soil of the Deccan suits cotton; the Indo-Gangetic plains are among the most fertile and densely populated regions), many rivers, forests, minerals (India has nearly 8% of the world's iron-ore reserves, plus coal, natural gas, bauxite, copper and more).

Pressure and dichotomy: development has strained finite resources. India faces both poverty-induced degradation and pollution from affluence and industry. Concerns include air pollution, water contamination, soil erosion, deforestation and wildlife extinction.

Priority issues: land degradation; biodiversity loss; air pollution, especially vehicular pollution in cities (motor vehicles rose from about 3 lakh in 1951 to 35 crore in 2022, with two-wheelers and cars about 85%); fresh water management; solid waste management. The CPCB has identified seventeen categories of significantly polluting industries.

Land degradation causes: deforestation; unsustainable fuelwood and fodder extraction; shifting cultivation; encroachment; forest fires and over-grazing; poor soil conservation; improper crop rotation; indiscriminate agro-chemicals; poor irrigation management; excessive groundwater extraction.

Community action such as the Chipko and Appiko movements has protected forests.

Worked example

Suppose a city's air quality worsens every winter. Using NCERT's analysis, what is likely the main urban source, and why does it matter most? [3 marks]

Try it first, then show the solutionSolution

1. Vehicles are the major contributors to urban air pollution.
2. Vehicle numbers grew from about 3 lakh (1951) to 35 crore (2022).
3. Vehicular emissions are ground-level sources, so they have the maximum impact on people.

Answer: Vehicular emissions, which act at ground level where people breathe.

Sustainable development: meaning and conditions

NCERT section 7.4

UNCED / Brundtland definition: development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs. The key ideas are needs (linked to fair distribution of resources: meeting the basic needs of all is a moral issue) and future generations.

Edward Barbier: sustainable development directly raises the material standard of living of the poor at the grassroots (income, education, health, sanitation, water) and aims to reduce absolute poverty through lasting livelihoods that minimise resource depletion, environmental degradation, cultural disruption and social instability.

The present generation should hand over at least as large a stock of "quality of life" assets as it inherited, by conserving natural assets, preserving the regenerative capacity of ecosystems and not imposing added costs or risks on future generations.

Herman Daly's conditions: (i) limit population within the environment's carrying capacity (like a ship's Plimsoll line); (ii) technological progress should be input-efficient, not input-consuming; (iii) extract renewable resources no faster than they regenerate; (iv) deplete non-renewable resources no faster than renewable substitutes are created; (v) correct inefficiencies from pollution.

In 2015 the UN set 17 Sustainable Development Goals to be achieved by 2030.

Worked example

Suppose a coal-rich state uses all its coal royalties for current consumption, with no investment in solar power. Which of Herman Daly's conditions does it violate? [1 mark]

Try it first, then show the solutionSolution

1. Coal is non-renewable.
2. Its depletion is not matched by creation of renewable substitutes.

Answer: Condition (iv): non-renewable depletion should not exceed creation of renewable substitutes.

Strategies for sustainable development

NCERT section 7.5

• Non-conventional energy: thermal plants emit carbon dioxide and fly ash; hydro projects flood forests and disrupt river flows; so tap wind and solar.
• LPG and gobar gas in rural areas: replace wood and dung cakes (which cause deforestation and indoor pollution); LPG is clean; gobar gas plants produce fuel and slurry that is excellent organic fertiliser.
• CNG in urban areas: Delhi's use of CNG in public transport significantly lowered air pollution.
• Wind power: no adverse impact; high initial cost recovered over time.
• Solar power through photovoltaic cells: pollution-free; very useful for remote areas.
• Mini-hydel plants: small plants on mountain streams, environment-friendly, meeting local needs.
• Traditional knowledge and practices: eco-friendly systems of agriculture, health care (e.g. herbal medicine) and housing.
• Biocomposting: compost from organic wastes, faster with earthworms (vermicomposting).
• Biopest control: neem-based pesticides, mixed cropping and crop rotation, and protecting predators such as snakes, owls, peacocks and lizards.

Worked example

Suppose a village uses dung cakes and firewood for cooking. Suggest two sustainable alternatives and explain their benefits. [3 marks]

Try it first, then show the solutionSolution

1. Gobar gas plant: dung produces gas for cooking; slurry becomes organic fertiliser; no smoke.
2. LPG (subsidised): clean fuel, cutting indoor pollution and wood use.
3. Both reduce deforestation and improve health.

Answer: Gobar gas and LPG reduce deforestation and indoor pollution.

Environment and Sustainable Development in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• Functions of the Environment, Carrying Capacity, Global Warming and Ozone Depletion
• Sustainable Development: Meaning, Conditions, Strategies and India's Environment

Environment and Sustainable Development: key facts

Sustainable extraction (renewable)

Rate of extraction ≤ rate of regeneration

Sustainable depletion (non-renewable)

Rate of depletion ≤ rate of creation of renewable substitutes

Waste condition

Waste generated ≤ absorptive capacity of the environment

Brundtland definition

Meet present needs without compromising future generations' ability to meet theirs

Four functions of environment

Supply resources; assimilate waste; sustain life; aesthetic services

Key facts (NCERT)

Since 1750	CO2 +31%, CH4 +149%
Ozone	about −5% (1979-90)
Vehicles	3 lakh (1951) → 35 crore (2022)
Iron ore	India about 8% of world
SDGs	17 (2015, for 2030)

How the board asks Environment and Sustainable Development

The question patterns to expect, and the method that works for each.

Tricks to remember Environment and Sustainable Development

Short memory aids. Say each one aloud once, then use it on a question the same day.

• SAGA functions

  Supply resources, Assimilate waste, Genetic diversity (sustain life), Aesthetic services.

  Use it when: Functions of the environment.

• Plimsoll line

  An economy, like a ship, needs a load limit: carrying capacity.

  Use it when: Daly's first condition.

• Kyoto heat, Montreal ozone

  Kyoto = greenhouse gases; Montreal = CFCs.

  Use it when: Agreements.

• Five Daly rules

  Population limit, efficient technology, renewables ≤ regeneration, non-renewables ≤ substitutes, fix pollution.

  Use it when: Sustainability conditions.

Environment and Sustainable Development: board-level solved questions

Ordered from board level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section E style)

Read the situation, then answer every part. In the board paper this is a 4-mark question split into 1 + 1 + 2 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Environment and Sustainable Development

The slips examiners see most often, and what to write instead.

• ✗Mistake: Confusing carrying capacity with absorptive capacity

  Similar ideas.

  ✓Do this: Carrying capacity covers both extraction within regeneration and waste within absorptive capacity; absorptive capacity is only about waste.

  Usually costs: 1 mark.

• ✗Mistake: Mixing up global warming and ozone depletion

  Both are atmospheric.

  ✓Do this: Global warming: greenhouse gases trap heat. Ozone depletion: CFCs thin the stratospheric ozone layer, letting in UV.

  Usually costs: 1-2 marks.

• ✗Mistake: Giving the definition of sustainable development without "future generations"

  Shortening.

  ✓Do this: Include both "present needs" and "future generations".

  Usually costs: 1 mark.

• ✗Mistake: Listing strategies without explaining benefits

  Rote lists.

  ✓Do this: Add one line on how each strategy helps.

  Usually costs: ½ mark each.

• ✗Mistake: Mixing Kyoto and Montreal

  Two agreements.

  ✓Do this: Kyoto (1997): greenhouse gases; Montreal: ozone-depleting substances.

  Usually costs: 1 mark.

NCERT exercise guide: Environment and Sustainable Development

What each exercise in the NCERT chapter tests, how to approach it, and a question of the same kind solved step by step. Questions here are written in our own words.

Environment and Sustainable Development: previous year questions

• Asked in 2 of the 2 board papers we hold (2026 to 2026), on average 3.5 marks per paper; 4 questions in all, counting OR alternatives. In 4 of 4 sample papers.

Counted from the real papers on our previous year papers page, not estimated. Average marks are over every board paper we hold, with an OR pair counted once. Chapter tags are ours.

Solved board questions from Environment and Sustainable Development

Real questions from recent papers. Try each one first, then open our step-by-step solution with marks per step.

Every Environment and Sustainable Development question, by year

Practice questions on Environment and Sustainable Development

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQBoard level

   The ability of the environment to absorb degradation is called:
   (a) carrying capacity
   (b) absorptive capacity
   (c) regeneration
   (d) biodiversity

   Hint

   Absorbs.

   Answer

   (b) absorptive capacity

2. Q2 · 1 mark · MCQBoard level

   Which of the following is NOT a function of the environment?
   (a) Supplies resources
   (b) Assimilates waste
   (c) Fixes market prices
   (d) Provides aesthetic services

   Hint

   Four functions.

   Answer

   (c)

3. Q3 · 3 marks · Short answerBoard level

   Distinguish between renewable and non-renewable resources with examples.

   Hint

   Exhaustion.

   Answer

   Renewable resources can be used without being exhausted if used carefully (forests, fish); non-renewable resources are exhausted by extraction and use (coal, petroleum).

4. Q4 · 3 marks · Short answerBoard level

   State any four factors responsible for land degradation in India.

   Hint

   NCERT list.

   Answer

   Deforestation; unsustainable fuelwood and fodder extraction; shifting cultivation; over-grazing and forest fires (also improper crop rotation, agro-chemicals, poor irrigation management, groundwater over-extraction).

5. Q5 · 3 marks · Short answerHarder board level

   Explain ozone depletion: cause, effect and international response.

   Hint

   CFCs.

   Answer

   CFCs and halons release chlorine and bromine that destroy stratospheric ozone; more UV reaches the earth, causing skin cancer and harming phytoplankton and plants; the Montreal Protocol banned CFCs and other ozone-depleting chemicals.

6. Q6 · 3 marks · Short answerHarder board level

   Explain the opportunity costs of environmental degradation.

   Hint

   Water, research, health.

   Answer

   Polluted and dried-up water sources make water an economic good; exhausted resources force spending on research for new ones; poor air and water raise disease and health spending; global problems add government commitments.

7. Q7 · 3 marks · Short answerHarder board level

   Explain any three strategies of sustainable development suitable for rural India.

   Hint

   Fuel, farming.

   Answer

   Gobar gas plants and LPG instead of wood and dung cakes; biocomposting and vermicomposting instead of chemical fertilisers; biopest control (neem-based pesticides, crop rotation, protecting predators). Mini-hydel plants also suit hilly areas.

8. Q8 · 1 mark · Assertion-reasonHOTS / competency

   Assertion (A): Environmental problems were less serious in early civilisations.
   Reason (R): The demand for environmental resources and services was then less than their supply.
   (a) Both true and R explains A (b) Both true, R does not explain A (c) A true, R false (d) A false, R true

   Hint

   Supply-demand reversal.

   Answer

   (a)

9. Q9 · 4 marks · Short answerHOTS / competency

   Suppose a country argues: "We must grow fast now and clean up later." Evaluate this using the concept of sustainable development.

   Hint

   Future generations.

   Answer

   Sustainable development requires meeting present needs without compromising future generations. "Grow now, clean later" depletes resources and exceeds absorptive capacity, imposing costs on future generations (health, lost resources) and may cause irreversible damage; it violates Daly's conditions. Growth should be input-efficient and within regeneration limits.

10. Q10 · 3 marks · Short answerHarder board level

    Explain the role of CNG in reducing urban air pollution with NCERT's example.

    Hint

    Delhi.

    Answer

    CNG is a cleaner fuel than petrol or diesel; Delhi's shift of public transport to CNG significantly lowered air pollution, and many other cities have followed.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.What are biotic and abiotic elements?Show answer

   Living elements (plants, animals) and non-living elements (air, water, land, rocks, sunlight).

2. 2.What is carrying capacity?Show answer

   Extraction within regeneration and waste within absorptive capacity, so the environment can keep performing its functions.

3. 3.What share of India's water does NCERT say is polluted?Show answer

   Seventy per cent.

4. 4.By how much have CO2 and methane risen since 1750 (NCERT)?Show answer

   31% and 149%.

5. 5.What causes ozone depletion?Show answer

   Chlorine and bromine compounds from CFCs and halons.

6. 6.Name the five priority environmental issues for India.Show answer

   Land degradation, biodiversity loss, urban (vehicular) air pollution, fresh water management, solid waste management.

7. 7.Who gave five conditions for sustainable development?Show answer

   Herman Daly.

8. 8.When were the 17 SDGs adopted, and for which year?Show answer

   2015, to be achieved by 2030.

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Can you define the environment and give biotic and abiotic examples?
• ☐Can you explain the four functions?
• ☐Can you explain carrying and absorptive capacity?
• ☐Can you explain why environmental problems are recent?
• ☐Can you explain causes and effects of global warming?
• ☐Can you explain ozone depletion and the Montreal Protocol?
• ☐Can you list India's five priority issues?
• ☐Can you give the Brundtland definition?
• ☐Can you state Daly's five conditions?
• ☐Can you explain five strategies for sustainable development?

Environment and Sustainable Development: frequently asked questions