Solutions-Class 8-Science-Chapter-8-Pollution-Maharashtra Board

a. Air pollution-Due to smog
b. Water pollution-Water contaminated due to bacteria or virus.
c. Air pollution- Due to Pollens
d. Soil pollution-due to chemicals
e. Air pollution- due to toxic smoke from vehicle.

• Nilesh is a student of std. VIII and lives in urban area. It takes about an hour to go to the school by bus. He faces the heavy traffic of two wheelers, four wheelers, rickshaws, buses while going to school. (Heavy Traffic-Air pollution) 
• He is facing the problem of asthmasince last few days. (Air pollution) 
• Doctors recommended him to stay away from urban area. Since then, his mother sent him to the village of his maternal uncle. Nilesh saw the heaps of garbage at many places in village. (Land Pollution)
• Foul smell of human and animal wastes was present at many places. (Air and soil pollution) 
• Blackish water with foul smell was flowing in a stream. (Poor sewage management-Water pollution) 
• He developed some abdominal disease with in few days. (Unsafe drinking water-Water pollution)

False. Because, even if washing of soiled clothes is done in running water, the dirt and the waste materials stick on cloth will get add in to the water and this certainly will cause water pollution.

True- In india most of the electricity is generated by thermal power plant.These power plants are run by burning coal, nuclear energy & burning of fossil fuel. The power generation plants thus cause lots of air pollution. More the electricity is used by using more appliances, there will be more pollution. However, only power generation through solar energy & wind energy cannot cause pollution.

Pollution is contamination of natural environment and any undesirable change that takes place in the environment which is harmful to both living and non-living things.

Pollutants are the harmful chemicals and substances which affect the normal functioning of ecosystem, which cause pollution and have harmful effect on living organism. For example, nitrogen oxides, sulphur oxides, carbon monoxide, pesticides etc.

Gases such as sulphur dioxide, sulphur trioxide and nitrogen dioxide, when present in air, combine with the water droplets present in the atmosphere to form acid droplets. These droplets remain suspended in air and fall down on the earth along with rain, thereby making the rain acidic. Such rain is called acid rain.

The increase in the average temperature of the earth’s surface due to the increase in concentration of greenhouse gases such as carbon dioxide, methane, etc. is called greenhouse effect.

• The gases (CO₂, CH₄, N₂O and CCI₂F₂) contributing to greenhouse effect are called greenhouse gases.
• More and more burning of fossil fuels and allied activities by humans cause more and more greenhouse effect.
• The worst impact of greenhouse effect is global warming and climate change.

Pollutants which are visible to our naked eyes are called visible pollutants. For example, sewage, plant and animal wastes, pesticides, plastic, sand, metal refuse etc.

Invisible pollutants are pollutants which are dissolved in water or mixed with air, not visible to our naked eyes are called Invisible pollutants. For example, insecticides spread on crops, fungi, viruses, bacteria, gases like carbon monoxide, nitrogen dioxide, toxic compound which are soluble in water etc.

Sources of air pollution:

• Burning of fuel like wood, kerosene.
• Construction of new building & demolishing of structures create dust pollution.

Sources of water pollution:

• Washing of clothes in flowing water bodies.
• Release of domestic sewage into water bodies.
• Plastics thrown in water bodies.

Sources of soil pollution:

• Spraying of pesticides and insecticides on plants.
• Mixing of wastes of animals and plants.
• Garbage heaps, medical scrap.

• Most of the vehicles are run on fossil fuels like petrol and diesel. These fossil fuels are burnt in vehicles to produce energy which results in the production of smoke.
• More than 50% of the air pollution is caused by vehicular traffic.
• Automobile exhausts contains harmful gases like carbon monoxide, hydrogen, nitrogen oxide, particulate matter, ammonia and sulphur dioxide. Therefore, vehicles are said to be the major contributors to air pollution. 
• There are various other kinds of vehicles which cause least or no pollution at all, for example- bicycle, vehicles run on CNG, electric cars, metro etc. These types of vehicles are eco-friendly.

The natural reasons of water pollution are:

• Presence of aquatic weeds which depletes the oxygen content of water bodies.
• Excessive algal growth.
• Mud and sludge which are added to water bodies due to river currents and their diversions.
• Growth of microbes like bacteria and fungi on dead and decaying matter present in water bodies.

Some of the measures that can be taken to prevent air pollution are as follows:

(i) Use of clean fuels such as CNG, LPG and unleaded petrol in public and private transport.

(ii) Use of renewable sources of energy such as solar, wind, and hydel energy.

(iii) Planting more and more trees to prevent pollution.

(iv) Preventing burning of dry leaves and using them in composting.

(iv) Effective pollution controlling equipment like dust collectors, electrostatic precipitators, wet scrubbers, etc. should be used.

Because of greenhouse effect, there is increase in the global temperature. The heat on the earth remains trapped due to envelope of greenhouse gases. The percentage of carbon dioxide and methane is constantly increasing and hence there is increase in the temperature too. Thus the greenhouse effect is directly related to the global warming.

The greenhouse effect can be controlled by reducing the use of fossil fuels. Fossil fuels produce greenhouse gases on burning.

Air Pollution :

• Take care-Clean air. 
• Be a part of solution and not part of air Pollution

Water Pollution :

• Save fishes avoid diseases.
• Plastic makes water toxic.

Soil Pollution :

• Keeping land clean Health will win.
• Cleanliness is best for health

It is an activity based question. Kindly do it yourself.