Q1Multiple choice
Air is a mixture of various gases. One of the gases is 21% part of the air and is essential for the survival of human beings. This gas is
- (a)nitrogen
- (b)oxygen
- (c)ozone
- (d)argon
Show answer
(b) oxygen
Chapter 18
Class 8 Science · 32 questions · 31 with answers
Questions
Q2Multiple choice
Which of the following is not a source of air pollution?
- (a)automobile exhaust
- (b)burning of firewood
- (c)windmill
- (d)power plant
Show answer
(c) windmill
Q3Multiple choice
Boojho wishes to contribute in reducing air pollution. Which vehicle should he use for going to school?
- (a)car
- (b)school bus
- (c)autorickshaw
- (d)scooter
Show answer
(b) school bus
Q4Multiple choice
Which of the following is not a way to conserve water?
- (a)replace
- (b)reduce
- (c)reuse
- (d)recycle
Show answer
(a) replace
Q5Multiple choice
The type of pollution which is likely to affect Taj Mahal in Agra to a greater extent is
- (a)air pollution
- (b)water pollution
- (c)soil pollution
- (d)noise pollution
Show answer
(a) air pollution
Q6Multiple choice
Incomplete combustion of fuel such as petrol and diesel gives
- (a)nitrogen oxide
- (b)sulphur dioxide
- (c)carbon monoxide
- (d)carbon dioxide
Show answer
(c) carbon monoxide
Q7Multiple choice
The phenomenon of marble cancer is due to
- (a)soot particles
- (b)CFCs
- (c)fog
- (d)acid rain
Show answer
(d) acid rain
Q8Multiple choice
Potable water is the water which is
- (a)obtained from a river.
- (b)obtained from a lake.
- (c)pure and fit for drinking.
- (d)used only for washing clothes. P OLLUTION O F AI R AND WATER 105
Show answer
(c) pure and fit for drinking.
Q9Multiple choice
Which of the following procedures will give you water free from all impurities?
- (a)adding chlorine tablets
- (b)distillation
- (c)boiling
- (d)filtration
Show answer
(b) distillation
Q10Multiple choice
A pond contains clean water. Which of the following activities will produce least pollution of water?
- (a)washing clothes in the pond
- (b)animals bathing in the pond
- (c)washing motor vehicles in the pond
- (d)swimming in the pond.
Show answer
(d) swimming in the pond.
Q11Multiple choice
Trees help in reducing the pollution of our environment. Lakhs of trees are planted by people in the month of July every year. The occasion is called
- (a)forest Conservation Day
- (b)plantation month
- (c)Van Mahotsav
- (d)wildlife week
Show answer
(c) Van Mahotsav
Q12Multiple choice
Which of the following is not a green house gas?
- (a)nitrogen gas
- (b)water vapour
- (c)methane gas
- (d)carbon dioxide
Show answer
(a) nitrogen gas
Q13Very short answer
Name the chemicals which are used in refrigerators and air conditioners and damage ozone layer when released in air.
Show answer
Chlorofluorocarbons.
Q14Very short answer
Name any two sources which cause air pollution due to suspended particulate matter.
Show answer
(i) Combustion of fuel (ii) Industrial activities
Q15Very short answer
Name two gases which are mainly responsible for acid rain?
Show answer
(i) sulphur dioxide (ii) nitrogen dioxide
Q16Very short answer
The quality of air at various locations is monitored regularly by government and other agencies? In what way can you use these data?
Show answer
These data can be used to generate awareness about air pollution among people.
Q17Very short answer
Combustion of fossil fuels generates a lot of air pollution. Can you suggest any two alternative sources of energy which do not cause any pollution?
Show answer
Solar energy and wind energy.
Q18Very short answer
Name any two water pollutants which are toxic for plants and animals. 106 E XEMPLAR PROBLEMS
Show answer
Lead, arsenic, fluorides (any two) SHORT ANSWER QUESTIONS
Q19Short answer
A lot of dry leaves are collected in a school garden and are burnt every day. Do you think that it is right to do so? If not, what should be done to dispose off the dry leaves?
Show answer
It is not right to burn dry leaves as it causes air pollution. The right way to dispose off the dry leaves is to convert them into compost.
Q20Short answer
The level of air pollution is higher at a busy traffic intersection. Why?
Show answer
A large number of automobiles stop for a short period at red light through out the day and release a large quantity of gases which create air pollution.
Q21Multiple choice
Fill in the blanks with the help of words given in bracket after each sentence.
- (a)When air is contaminated by ________ substances which have a ________ effect on both the ________ and ________, it is referred to as ________. (air pollution, harmful, living, unwanted, non-living, pollutants).
- (b)Many ________ are responsible for causing ________ pollution. Petroleum ________ are a major source of ________ pollutants like ________ and ________. (sulphur dioxide, refineries, industries, nitrogen dioxide, gaseous, liquid, people, air).
- (c)While ________ your teeth, leaving the ________ running may waste several ________ of water. (tap, litres, brushing, washing, drops)
- (d)Water which is suitable for _________ is called ________ water. (washing, bathing, drinking, potable, soft). (e) Water which looks clean still has disease carrying ________ and ________ impurities. (insects, microorganism, particles, dissolved, harmful).
Show answer
(a) When air is contaminated by ________ substances which have a ________ effect on both the ________ and ________, it is referred to as ________. (air pollution, harmful, living, unwanted, non-living, pollutants).
(b) Many ________ are responsible for causing ________ pollution. Petroleum ________ are a major source of ________ pollutants like ________ and ________. (sulphur dioxide, refineries, industries, nitrogen dioxide, gaseous, liquid, people, air).
(c) While ________ your teeth, leaving the ________ running may waste several ________ of water. (tap, litres, brushing, washing, drops)
(d) Water which is suitable for _________ is called ________ water. (washing, bathing, drinking, potable, soft). (e) Water which looks clean still has disease carrying ________ and ________ impurities. (insects, microorganism, particles, dissolved, harmful).
Q22Multiple choice
Match the items of Column A with those of Column B. Column A Column B (a) sulphur dioxide
- (i)damage ozone layer (b) carbon dioxide
- (ii)reduces oxygen- carrying capacity of blood (c) carbon monoxide
- (iii)acid rain. (d) chlorofluorocarbons
- (iv)green house gas P OLLUTION O F AI R AND WATER 107
Show answer
(i) damage ozone layer (b) carbon dioxide
(iii) acid rain. (d) chlorofluorocarbons
(ii) reduces oxygen- carrying capacity of blood (c) carbon monoxide
(iv) green house gas P OLLUTION O F AI R AND WATER 107
Q23Multiple choice
Find out the wrong statements and write them in their correct form.
- (a)We can survive for some time without air but we cannot survive even for a few minutes without food.
- (b)A brick kiln emits lot of smoke and other harmful gases causing air pollution.
- (c)Carbon monoxide is produced by complete burning of fuels such as coal, petrol, diesel.
- (d)Chlorination is a commonly used chemical method for killing germs in water. (e) Water which is suitable for drinking is called soft water.
Show answer
(b) A brick kiln emits lot of smoke and other harmful gases causing air pollution.
(d) Chlorination is a commonly used chemical method for killing germs in water. (e) Water which is suitable for drinking is called soft water.
(a) We can survive for some time without air but we cannot survive even for a few minutes without food.
(c) Carbon monoxide is produced by complete burning of fuels such as coal, petrol, diesel.
Q24Multiple choice
In the following statements, the underlined words are jumbled up. Write them in their correct form.
- (a)Air contains 78% ginroten and 21% gonexy.
- (b)Vehicles produce high level of pollutants like carbon dioxide, nitrogen oxides, nobrac moondexi and mosek.
- (c)Carbon dioxide, thaneme, nitrous oxide and water vapour are known as heengrouse sesga.
- (d)Gangotri glacier in Himalaya has started melting because of lablog ringwam. (e) Whenever harmful substances such as wagese, toxic chemicals, silt, etc. get mixed with water, the water becomes potdulle.
Show answer
(a) Air contains 78% ginroten and 21% gonexy.
(b) Vehicles produce high level of pollutants like carbon dioxide, nitrogen oxides, nobrac moondexi and mosek.
(c) Carbon dioxide, thaneme, nitrous oxide and water vapour are known as heengrouse sesga.
(d) Gangotri glacier in Himalaya has started melting because of lablog ringwam. (e) Whenever harmful substances such as wagese, toxic chemicals, silt, etc. get mixed with water, the water becomes potdulle.
Q25Long answer
What do CFCs stand for? Name some devices where CFCs are used. Why CFCs are considered as pollutants?
Show answer
Hint: – CFCs stand for chlorofluorocarbons. – Refrigerators, air conditioners etc. – Damage the ozone layer of the atmosphere.
Q26Long answer
Why is it advised that industries should switch over to cleaner fuels such as CNG and LPG in the Taj Mahal Zone in Agra?
Show answer
Hint: Pollutants in air are discolouring white marble of Taj Mahal. The pollutants like sulphur dioxide and nitrogen dioxide react with the water vapour present in the atmosphere to form sulphuric acid and nitric acid respectively.
Q27Long answer
It is said, “CO2 contributes to global warming.” Explain.
Show answer
Hint: CO2 takes heat and does not allow it to escape into space. As a result, the average temperature of the earth’s atmosphere is gradually increasing.
Q28Long answer
We should plant trees and nurture the ones already present in the neighbourhood. Why?
Show answer
Hint: – To reduce air pollution. – To control global warming.
Q29Long answer
Explain the traditional way of purifying water to make it fit for drinking. 108 E XEMPLAR PROBLEMS
Show answer
Hint: 1. Filtration 2. Boiling 3. By adding chlorine tablets. ANSWERS 157
Q30Long answer
How can we reduce, reuse and recycle water?
Show answer
Hint: Reduce – While brushing your teeth, bathing etc.. we should not keep our taps on. Reuse – Water used for washing vegetables, rice etc. can be used for gardening. Recycle – Dirty water can be recycled after purification.
Q31Multiple choice
Read the paragraph and answer the questions following it. Water is essential for life. Without water there would be no life. We usually take water as granted for its purity, but we must ensure the quality of water. Pollution of water originates from human activities. Through different paths, pollution reaches to ground water. Easily identified source or place of pollution is called as point source, e.g.– municipal and industrial discharge pipes, where pollutants enter the water source. Non–point sources of pollution are those where a source of pollution can not be easily identified, e.g.– agricultural run off, acid rain etc.
- (i)How do you classify the various sources of water pollution?
- (ii)What are the point sources of water pollution?
- (iii)Name any two non-point sources of water pollution?
Show answer
(i) How do you classify the various sources of water pollution?
(ii) What are the point sources of water pollution?
(iii) Name any two non-point sources of water pollution?
Q32Long answer
Complete the crossword puzzle with the help of clues given below: Fig. 18.1 P OLLUTION O F AI R AND WATER 109 Across Down 1. Pollutant which was used 2. This layer protects in refrigerators and air us from harmful conditioners. (18) ultraviolet rays. (5) 3. Produced on incomplete 4. It is essential for combustion of fuels. (14) combustion. (6) 5. Disease which is caused by drinking contaminated water. (7) 6. This chemical protects 7. River which is famous our crops and is in India and sustains washed into water most of the northern, bodies from the field. (9) central and eastern Indian population. (5)
This question refers to a figure in the original PDF.