CBSE Class 11 Chemistry Chapter 14: Environmental Chemistry NCERT Solutions

Reviewed by NCERT Help Editorial Team · Updated on 29 Jul 2026

NCERT Solutions PDF Class 11 PDF

This resource provides detailed NCERT Solutions for Class 11 Chemistry, Chapter 14, focusing on Environmental Chemistry. It covers fundamental concepts such as the definition of environmental chemistry, the causes and effects of tropospheric pollution including acid rain and smog, the comparative toxicity of carbon monoxide and carbon dioxide, and the primary gases responsible for the greenhouse effect. The solutions explain the chemical processes involved, the impact of pollutants on human health and the environment, and the mechanisms behind phenomena like global warming. These solutions are designed to help students grasp complex environmental issues from a chemical perspective, aiding in thorough exam preparation and revision.

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Quick info

Board	CBSE
Class	Class 11
Subject	Chemistry
Session	2026
Language	English
Type	NCERT Solutions
Chapter	Chapter 14

Chapter summary

Chapter 14 of the NCERT Class 11 Chemistry syllabus, Environmental Chemistry, is explained through these solutions. It defines environmental chemistry and elaborates on key pollution types like tropospheric pollution, detailing pollutants such as oxides of sulfur and nitrogen, hydrocarbons, and carbon oxides. The solutions also address the dangers of CO versus CO2, and list the principal gases contributing to the greenhouse effect, including CO2, CH4, H2O, N2O, O3, and CFCs.

Learning outcomes

Understand the definition and scope of environmental chemistry.
Explain the causes and consequences of tropospheric pollution.
Analyze the formation and impact of acid rain.
Compare the toxicity of carbon monoxide and carbon dioxide.
Identify the major greenhouse gases and their role in global warming.

Topics covered

Paper topics

Environmental Chemistry Definition
Tropospheric Pollution
Gaseous Pollutants (SOx, NOx, CO, CO2, Hydrocarbons)
Acid Rain
Particulate Matter Pollution
Smog (Photochemical and Classical)
Carbon Monoxide Toxicity
Greenhouse Effect
Greenhouse Gases (CO2, CH4, H2O, N2O, O3, CFCs)
Global Warming

Important topics

Tropospheric Pollution
Acid Rain Formation and Effects
Carbon Monoxide vs. Carbon Dioxide Toxicity
Greenhouse Effect and Major Greenhouse Gases

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Questions and Solutions

Question 14.1

Define environmental chemistry.

Solution: Environmental chemistry is defined as the study of chemical and biochemical processes that occur in the natural environment. It encompasses the investigation of the origin, transport, reactions, effects, and ultimate fate of various chemical species within different environmental spheres like the atmosphere, hydrosphere, and lithosphere.

Question 14.2

Explain tropospheric pollution in approximately 100 words.

Solution: Tropospheric pollution refers to the contamination of the lowest layer of the Earth's atmosphere, the troposphere, by undesirable chemical substances. Major gaseous pollutants include oxides of sulfur (SO2, SO3) and nitrogen (NO, NO2), primarily from burning fossil fuels. These oxides react with atmospheric moisture and oxygen to form sulfuric acid (H2SO4) and nitric acid (HNO3), leading to acid rain, which damages ecosystems and causes respiratory issues. Hydrocarbons, also from fuel combustion, can be carcinogenic. Carbon monoxide (CO) is highly toxic as it reduces blood's oxygen-carrying capacity. Carbon dioxide (CO2), while not acutely toxic, contributes to global warming by trapping infrared radiation. Particulate pollutants like smoke and dust can block nasal passages and cause respiratory ailments. Smog, a combination of smoke and fog, reduces visibility, while photochemical smog causes eye irritation and plant damage.

$2SO_{2(g)} + O_{2(g)} + 2H_2O_{(l)} \longrightarrow 2H_2SO_{4(aq)}$

$4NO_{2(g)} + O_{2(g)} + 2H_2O_{(l)} \longrightarrow 4HNO_{3(aq)}$

Question 14.3

Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?

Solution: Carbon monoxide (CO) is significantly more dangerous than carbon dioxide (CO2) primarily due to its physiological effects on humans. While CO2 is a greenhouse gas and can be harmful at very high concentrations, CO is a potent poison. This is because CO has a much higher affinity (about 200-250 times greater) for haemoglobin in the blood than oxygen. When inhaled, CO binds with haemoglobin to form carboxyhaemoglobin (COHb), a complex that is far more stable than oxyhaemoglobin. This binding drastically reduces the blood's capacity to transport oxygen to vital organs like the brain and heart. Even a small concentration of CO in the air can lead to headaches, visual disturbances, nervousness, and cardiovascular problems. In higher concentrations, it can cause unconsciousness and death.

Question 14.4

List gases which are responsible for the greenhouse effect.

Solution: The greenhouse effect is primarily caused by certain gases in the Earth's atmosphere that trap heat. These gases, known as greenhouse gases, include:

Carbon dioxide (CO2)
Methane (CH4)
Water vapour (H2O)
Nitrous oxide (N2O)
Ozone (O3)
Chlorofluorocarbons (CFCs)

These gases allow sunlight to pass through and warm the Earth's surface, but they absorb and re-emit the infrared radiation (heat) escaping from the Earth, thus warming the atmosphere.

Common mistakes

Confusing the relative toxicity of carbon monoxide and carbon dioxide.
Not fully understanding the chemical reactions leading to acid rain.
Incomplete listing of greenhouse gases.
Overlooking the role of hydrocarbons and particulate matter in pollution.

Revision tips

Focus on understanding the chemical reactions behind acid rain and smog formation.
Clearly differentiate between the health impacts of CO and CO2.
Memorize the list of major greenhouse gases and their sources.
Relate the concepts of pollution to real-world environmental issues.

Practice MCQs

Q1. What is the primary definition of environmental chemistry?

Q2. Which of the following is a major gaseous pollutant contributing to acid rain?

Q3. Why is carbon monoxide (CO) considered more dangerous than carbon dioxide (CO2)?

Q4. Which of these is NOT typically listed as a major greenhouse gas?

Q5. Photochemical smog can cause:

Frequently asked questions

What is environmental chemistry?

Environmental chemistry is the branch of chemistry that studies the chemical and biochemical processes occurring in the natural environment, including the origin, transport, reactions, effects, and fate of chemical species.

What causes tropospheric pollution?

Tropospheric pollution is caused by the presence of undesirable substances like oxides of sulfur, nitrogen, carbon, hydrocarbons, and particulate matter in the Earth's lowest atmospheric layer.

How does acid rain form?

Acid rain forms when oxides of sulfur (SO2, SO3) and nitrogen (NO, NO2) released into the atmosphere react with water, oxygen, and other chemicals to form sulfuric and nitric acids.

Why is carbon monoxide more dangerous than carbon dioxide?

Carbon monoxide is more dangerous because it binds to haemoglobin in the blood much more strongly than oxygen, forming carboxyhaemoglobin and severely reducing the blood's oxygen-carrying capacity, which can be fatal.

What are the main greenhouse gases?

The main greenhouse gases include carbon dioxide (CO2), methane (CH4), water vapour (H2O), nitrous oxide (N2O), ozone (O3), and chlorofluorocarbons (CFCs).

How can these NCERT solutions help in exam preparation?

These solutions provide clear, step-by-step explanations for each question, helping students understand the concepts of environmental chemistry, the causes and effects of pollution, and the chemical processes involved, which is crucial for exam revision.

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