Pollution - Standard 8 - General Science - Balbharati
Pollution
Q. 1 Following are some statements about pollution. Which type
of pollution do those express?
a. Fog seems to be appearing in Delhi during day hours.
Ans. Air pollution due to Smog.
b. Many times, vomiting and dysentery occurs after eating
‘pani puri’.
Ans. Water pollution - Contaminated food and water due to bacteria or virus.
c. Problem of sneezing occurs sometimes during visit to
garden.
Ans. Air pollution due to pollens.
d. Crop does not grow up in some areas.
Ans. Soil pollution.
e. People living in the busy squares face the problems like
short breathing and other respiratory problems.
Ans. Air pollution due to traffic.
Q. 2 Read the passage and identify the sentences expressing
types of pollution.
| Nilesh is a student of std. VIII and lives in an urban area. It takes about an hour to go to school by bus. He faces the heavy traffic of two-wheelers, four-wheelers, rickshaws, buses while going to school. He is facing the problem of asthma since the last few days. Doctors recommended him to stay away from the 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 the village. Foul smell of human and animal wastes was present at many places. Blackish water with a foul smell was flowing in a stream. He developed some abdominal disease within a few days. |
Ans.
1. It takes about an hour to go to the school by bus. (Nilesh is spending more time in polluted air due to heavy traffic.)
2. He faces heavy traffic. (Combustion of fossil fuels on a large scale.)
3. He is facing the problem of asthma since the last few days. (Harmful effect of air pollution)
4. The heaps of garbage at many places. (Land pollution due to solid waste)
5. Foul smell of human and animal wastes. (Air pollution due to biological factors)
6. Blackish water with a foul smell was flowing in a stream. (Water pollution due to improper sewage management)
7. He developed some abdominal disease within a few days. (Effect of water pollution on human health.)
Q. 3 Match the pairs from ‘A’ and ‘B’ columns and explain the effect of pollution on human health.
Ans.
| Column 'A' | Answers |
|---|---|
| Water containing cobalt | Paralysis |
| Methane gas | Skin cancer |
| Water containing lead | Mental retardation |
| Sulphur dioxide | Irritation of eyes |
| Nitrogen dioxide | Inflammation of eyes |
Q. 4 True
or false.
a. Water
does not get polluted by washing the cloths in running water of river.
Ans. False.
b. More
the use of electric appliances, more will be the pollution.
Ans. True.
5.
Answer the following.
a. What
is pollution?
Ans. Contamination of natural environment that will be harmful to ecosystems is called as pollution.
b. What
are pollutants?
Ans. Factors affecting natural functions of ecosystem and causing harmful effects on abiotic and biotic factors are called as pollutants.
c. What
is acid rain?
Ans.
1. Oxides of sulphur and nitrogen are released into atmosphere through burning of coal, timber and fuel oils.
2. Those oxides mix with rain water and form acids like sulphuric acid, nitric acid, nitrous acid, etc.
3.These acids mix with rain drops and snowflakes and come down as rain, called as acid rain.
d. What
is green house effect?
Ans.
1. Though CO2 is present in very less quantity in atmosphere, it plays very important role of absorption of solar heat.
2. Over the last 100 years, proportion of CO2 has been increased due to industrialization. Effect of this CO2 on the earth’s temperature is nothing but green house effect.
3. Similar to CO2 , nitrous oxide, methane and CFC also trap the heat. Collectively, these are called as green house gases.
e. Which
are visible pollutants known to you?
Ans. The pollutant which we can see with our naked eyes are called visible pollutants. E.g. Solid wastes, plastic bags and articles, the suspended things in the water bodies, metal refuse etc.
f. Which
are invisible pollutants?
Ans. The pollutants which are completely dissolved in water or mixed in the air, cannot be seen and hence they can be called invisible pollutants. E.g. the insecticides spread on the crops. Aerosols, many hazardous gases in the air, toxic compounds that are totally soluble in water, etc.
Q.6 Answer the following.
a. Give two examples of each of water, soil and air pollution from your residential area.
Ans. Students should write their own answer.
b. How does pollution occur due to vehicles? Give the names of vehicles causing less pollution.
Ans. Pollution from vehicles happens because when vehicles burn fuel like petrol or diesel, they release harmful gases and particles into the air. These pollutants include carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), and tiny particles called particulate matter (PM). These pollutants can harm the environment and our health.
Vehicles that cause less pollution are called "eco-friendly" or "green" vehicles. Some examples of such vehicles are electric cars, hybrid cars, and vehicles that use clean fuels like compressed natural gas (CNG) or hydrogen. These vehicles produce fewer harmful emissions and are better for the environment.
c. What are the natural reasons for water pollution?
Ans. Natural reasons for water pollution:
1. Aquatic weeds:
• Depletion in O2 level.
• Changes in natural qualities of water.
2. Decomposing matter:
• Decomposing bodies of plant, animals
3. Mud/sludge:
• River current and its diversion
4. Soil erosion:
• Many biotic and abiotic factors are added to water due to soil erosion.
5. Microbes like fungi and bacteria:
• grow on organic matter decaying in water.
6. Algae:
• Excessive algal growth pollutes water
7. Nematodes:
• Soil nematodes flow in with rain water
d. Suggest four preventive measures for air pollution.
Ans. 1. Smoke emerging from factories contains harmful particles. Hence, pollution controlling machinery should be used. Ex. Arresters, filters.
2. Proper disposal of stinking waste generated in cities.
3. Control on atomic tests, chemical weapons, etc.
4. Control / ban over CFC production.
e. Explain relation between green house effect and global warming.
Ans. Greenhouse effect occurs due to gases like CO2, methane, nitrous oxide, and CFCs. These gases help keep our planet warm by trapping some of the Sun's heat.
Due to factories and other reasons, we've added more of these gases into the atmosphere. It's like adding extra layers. This makes our Earth warmer than it should be. That's what we call global warming.
Because of this extra warmth, things are getting worst. Icebergs melt, sea levels rise, and it messes up our weather. Farmers have a tough time, and animals have to move because their homes get messed up.
So, the greenhouse effect is like a cozy blanket, but too many layers make our Earth too hot. That's global warming, and it's causing problems.
f. Construct two slogans each on air, water and soil pollution.
Ans. (Students can write their own slogans. Some examples are given below)
Air Pollution:
1. "Breathe Easy, Fight Air Pollution!"
2. "Clean Air, Healthy Life – Let's Clear the Skies!"
Water Pollution:
1. "Protect Our Waters, Preserve Our Future!"
2. "Clean Water, Clear Choice – Stop Pollution's Voice!"
Soil Pollution:
1. "Healthy Soil, Healthy Earth – Say No to Pollution!"
2. "Dig Deep, Act Now – Soil Pollution, We Must Plow!"
Q. 7 Classify the following pollutants into natural and manmade categories.
Sewage, dust, pollen grains, chemical fertilizers, vehicular smoke, algae, pesticides, waste of animals and birds.
| Natural | Man-made |
|---|---|
| Dust | Sewage |
| Pollen grains | Chemical fertilizers |
| Algae | Vehicular smoke |
| Waste of animals and birds | Pesticides |
