Free Pollution of Air and Water 01 Practice Test - 8th Grade
Question 1
______ is the combination of smoke and fog.
Cloud
Smog
Fly ash
Mist
SOLUTION
Solution : B
During winters, a thick fog-like layer is seen in the atmosphere especially in developing cities. This is called smog which is made up of smoke and fog. Smoke may contain oxides of sulphur and nitrogen which combine with other air pollutants and fog to form smog. Smog causes breathing difficulties such as asthma, cough and wheezing.
Question 2
Identify the air pollutant that can cause poisoning by readily combining with haemoglobin in the blood.
SOLUTION
Solution : A
Carbon monoxide is a colourless, odorless, tasteless, non-irritating and toxic gas formed by incomplete combustion of organic matter. It mainly causes adverse effects by combining with haemoglobin to form 'carboxyhaemoglobin' in the blood. This prevents haemoglobin from carrying oxygen to the tissues, leading to asphyxiation (choking and shortness of breath). In extreme conditions, it can also cause death.
Question 3
Select the oxides responsible for acid rain.
SOLUTION
Solution : A and C
Acid rain results when sulphur dioxide,SO2 and nitrogen oxides (NO and NO2) are released into the atmosphere and are transported by the wind and air currents. These oxides react with water, oxygen and other chemicals to form sulphuric acid and nitric acid. These acids fall to the ground as Acid Rain. While a small portion of the gases that cause acid rain is from natural sources such as volcanoes, most of it comes from the burning of fossil fuels.
Question 4
Dry cleaning of clothes gives off toxic fumes.
True
False
SOLUTION
Solution : A
Dry cleaning and regular laundering are two different processes. Dry-cleaning does not use water while laundering does. In dry cleaning, chemical solvents are used to get rid of hard stains like pen ink. Most solvents used are extremely toxic. Clothes after dry cleaning release corrosive acidic fumes that can damage the lungs. Hence, we should air our newly dry-cleaned clothes to minimise contact with these harmful fumes.
Question 5
What does the presence of a green layer over a water body in the image depict?
SOLUTION
Solution : B
The image depicts an eutrophic lake with algal blooms. Eutrophication is a process by which lakes or other water bodies become rich in nitrogenous nutrients due to excess run-off of fertilizers and animal wastes into them. Excessive nitrogen allows plant life (algae) to grow luxuriantly causing algal blooms. This cuts off oxygen supply to the residing fishes and other aquatic organisms.
Question 6
Which of the following is not present in the filtered water?
Salts
Germs
Minerals
Dirt
SOLUTION
Solution : D
Filtration is a physical method to remove impurities. Some dissolved salts and minerals remain in water even after filtration. This is because salts, germs, minerals and some other substances can pass through a filter paper or filtering candle.
Question 7
Identify the name of the process(es) that is used to obtain pure water.
SOLUTION
Solution : A, B, C, and D
There are many measures taken to make water fit for various purposes. Chlorination is a commonly used chemical method for purifying water. This is usually done by the municipality for household purposes. Similarly, filtration and boiling are also used for household purposes. Industrial laboratories require water that is completely free of dissolved salts. For this, most of the industries adopt the process of distillation as it is cheap and efficient.
Question 8
____ damage(s) the ozone layer of the atmosphere.
SOLUTION
Solution : D
Chlorofluorocarbons (CFCs) which are used in refrigerators, air conditioners and aerosol sprays are considered as pollutants. When CFCs escape into the atmosphere, they convert ozone(O3) to oxygen molecules(O2) and thus reduce the thickness of the ozone layer, which protects the Earth from the UV rays of the Sun.
Question 9
Air is contaminated by unwanted substances that have harmful effects on both living and non-living objects. This phenomenon is called _____.
SOLUTION
Solution : B
Air pollution is the phenomenon in which air is contaminated by unwanted substances. These contaminants have harmful effects on both living and non-living things.
Examples: Air pollution is caused by CO (carbon monoxide), oxides of sulphur etc.
CO reduces the lung capacity in humans while oxides of sulphur causes respiratory problems in humans and causes damage to buildings.
Question 10
Acid rain mainly contains
SOLUTION
Solution : C and D
Acid rain mainly consists of sulphuric acid and nitric acid, as sulphur oxides and nitrogen oxides combines with water vapour to form sulphuric acid and nitric acid respectively.