Environmental Chemistry Intext Questions with Answer NIOS

Environmental Chemistry Intext Questions with Answer NIOS National Institute of Open Schooling | NIOS

Environmental Chemistry Intext Questions with Answer NIO7

National Institute of Open Schooling (NIOS)
Sr. Secondary, Module-8
Lession-32: Environmental Chemistry Intext Questions with Answer NIOS


1. Define environment.

The word Environment is derived from the French word Environ which meaning surrounding. The environment can be stated as a system encompassing all biotic and abiotic elements affecting human life.

2. What are the two components of environment?

The two components of environment are biotic or living and abiotic or non-living component.

3. List three biotic components?

The three biotic components of an ecosystem are-
A. Autotrophs – produce their own food by using sunlight by the process of photosynthesis. Example plants, green algae.
B. Heterotrophs – these organisms depends on producers for their food. Example – humans.
C. Decomposers – consume, decompose dead and decaying matter. Example – hawk.

4. How do CFCs affect the ozone layer?

Chlorofluorocarbons (CFCs) move upward to the stratospheric layer of ozone and form chlorine in presence of ultraviolet radiation. This chlorine reacts with ozone and breaks it down to form oxygen. Thus, ozone layer gets damaged by CFC.

5. What are the different segments of environment?

The environment consists of various segments such as atmosphere, hydrosphere, lithosphere and biosphere.


1. Define a pollutant.

Toxic or harmful substances such as CO2, CO, SO2 that have adverse effect on the environment and living beings are known as pollutants.

2. Name two sources of natural pollution.

Two sources of natural pollution are-
A. Decay of plants and animals
B. Disintegration of rocks and soil

3. Define a secondary pollutant.

Secondary pollutants are pollutants which form in the atmosphere. These pollutants are not emitted directly from a source (like vehicles or power plants). Instead, they form as a result of the pollutants emitted from these sources reacting with molecules in the atmosphere to form a new pollutant.

4. What do you mean by environmental pollution?

Environmental pollution is the deterioration or unclean objectionable conditions in the quality of natural resources such as air water and soil because of the action or presence of unwanted substances in undesirable concentration.


1. What is atmospheric pollution?

Atmospheric pollution is defined as the introduction of harmful materials into the atmosphere is known as Atmospheric Pollution. Smog is the most common type of atmospheric pollutant which affects a major portion of the world.

2. Name two particulate pollutants.

Two  particulate pollutants are
A. Fluoride B. Lead

3. Name two gaseous pollutants?

Two gaseous pollutants are-
SO2 and CO2

4. Name one source which causes pollution due to methane.

Methane is an air pollutant that causes the Greenhouse effect.

5. Name two air pollutants which form photochemical smog.

Air pollutants that form photochemical smog are-
Hydrocarbons, Nitrogen oxides (NO2), Nitric oxide (NO), CO, PAN and O3.


1. What is smog?

Smog is a combination of fog, smoke, and fumes released by mills and factories, homes, and automobiles. Smog exists in two types-
Classical Smog occurs in the cool humid climate and Photochemical Smog result from the action of sunlight on unsaturated hydrocarbons and nitrogen oxides released by vehicles and industries.

2. Name two photochemical oxidants.

Two photochemical oxidants produced by atmospheric photochemical reactions are ozone and peroxyacetyl nitrate (PAN).

3. Name two gases which form acid rain.

Sulphur dioxide (SO2) and nitrogen dioxide (NO2) are the gases that react with water and oxygen and other gases to form acids like sulphuric and nitric, eventually resulting in acid rain.

4. Mention any four greenhouse gases.

Greenhouse gases that caused global warming are-
carbon dioxide, methane, Chlorofluorocarbons and nitrous oxide.

5. What are the sources of freons and halons in air?

Sources of freons are refrigerants and halons are fire extinguishers.

6. What effect does acid rain have on marble statues ?

Acid rain corrodes the marble statues.
CaCO3 + H2SO4 → CaSO4 + CO2 + H2O.

7. Mention one measure to control air pollution.

Air pollution can be controlled by minimizing and reducing the use of fire and fire products.


1. Define water pollution.

Water pollution occurs when harmful substances such as chemicals or microorganisms that contaminate a water body, degrading water quality and rendering it toxic to humans or the environment.

2. List any three anthropogenic sources of water pollution.

Anthropogenic sources of water pollution are domestic (sewage and wastewater), Industrial and agricultural wastes that go into the rivers, lakes, streams, and seas.

3. List the parameters indicating water pollution.

Following are the parameters indicating water pollution. A. Physical parameters: Colour, odour, turbidity, taste, temperature, and electrical conductivity constitute the physical parameters and are good indicators of contamination.
B. Chemical parameters: These include the number of carbonates, sulphates, chlorides, fluorides, nitrates, and metal ions. These chemicals form the total dissolved solids, present in water.
C. Biological parameters: The biological parameters include matter like algae, fungi, viruses, protozoa, and bacteria. The life forms present in water are affected to a good extent by the presence of pollutants.


1. Define eutrophication.

Eutrophication is the process in which excessive growth of algae occurs in a water body due to excessive minerals and nutrients. This process may end in oxygen depletion of the water body after the bacterial degradation of the algae. One example is an algal bloom. Eutrophication is usually induced by the discharge of nitrate or phosphate-containing detergents, fertilizers, or sewage into an aquatic system.


2. Why does aquatic life get killed in an eutrophied pond?

Fertilisers used in agriculture are washed into local water sources such as rivers and lakes by rainwater/surface run off In an eutrophied pond, the amount of nutrients are in lagre excess which enable algae to grow, leading to the formation of algal blooms at the surface of the water, blocking sunlight from reaching the bottom. Plants growing at the bottom of the pond are no longer able to photosynthesise to produce energy (and oxygen) and die. Bacteria decompose these plants aerobically, using up even more oxygen in the water for respiration. Oxygen levels become so low (hypoxic) that the water source is no longer able to support aquatic life.

3. What is the significance of BOD?

The significance of BOD are
a. BOD measures the amount of oxygen utilized by microorganisms for the process of decomposition of the organic matter in the water bodies.
b. It symbolizes the amount of organic pollution present in an aquatic ecosystem.
c. Also regulates the chemical oxidation (COD) of inorganic matter.
d. Used in sewage treatment or wastewater treatment to destroy and decay organic wastes through the aerobic organisms.
e. Detects the rate of respiration in living beings.

4. What is biomagnification?

Biomagnification refers to the accumulation of toxic substances in the food chain. The toxic chemicals that are released into the environment are absorbed by the lower organisms such as plants, earthworms, etc. These chemicals are then transferred to different trophic levels when lower organisms are eaten by other organisms.


1. What is refuse?

The different household wastes which are collected during household activities like cooking, cleaning, etc. are known as domestic wastes and urban wastes. Example: leaves, vegetable peels, excreta, etc.

2. Write the name of one insectide?

Substances that are used to kill insects are called insecticides. DDT or BHC is the insecticide

3. What is soil erosion?

Soil erosion is a process in which the top fertile layer of soil is lost. Due to soil erosion, the soil becomes less fertile. The top layer of soil is very light which is easily carried away by wind and water. The removal of topsoil by the natural forces is known as soil erosion. Various agents, like wind, water, deforestation, overgrazing by cattle, etc., cause soil erosion.


1. Write the names of those wastes which can be recycled.

Wastes that can be recycled are-
a. Paper Cardboard
b. Glass bottles and jars
c. Juice and milk cartons
d. Plastic bottles and containers
e. Steel and aluminum cans

2. Name the chemicals which are used in sedimentation of solid waste.

Potash Alumns and ferrous sulphate are used in the sedimentation of solid waste.

3. How the incrination cause to air pollutions?

The incomplete oxidation of Polychlorinated biphynyls (PCBs) may convert to toxic polychlorobidenzodioxins (PCDDs). The main problem of this process is air pollution due to incomplete oxidations.

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