Short Questions and Answers
One mark questions with answers
1. Photochemical smog is related to the pollution of
Answer: (d) air
2. Most important causative pollutant of soil maybe
(b) iron junks
(d) glass junks
Answer: (a) plastics
3. Taj Mahal is threatened due to the effect of
(b) sulphur dioxide
Answer: (a) chlorine
4. When huge amount of sewage is dumped into a river the BOD will
(b) remain unchanged
(c) slightly decrease
Answer: (c) slightly decrease
5. Which is a fungicide?
(c) Bordeaux mixture
Answer: (c) Bordeaux mixture
6. Rotenone is
(a) a bioherbicide
(b) an insect hormone
(c) a natural herbicide
(d) a natural insecticide
Answer: (b) an insect hormone
7.Which of the following is not produced as exhaust of vehicles?
(a) sulphur dioxide
(b) carbon dioxide
(c) carbon monoxide
(d) fly ash
Answer: (c) carbon monoxide
8. Which one of the following is a greenhouse gas?
(a) carbon dioxide
(b) carbon monoxide
Answer: (a) carbon dioxide
9. Smog produces
(d) Aluminium Ion
Answer: (d) Aluminium Ion
10. Depletion of ozone layer is due to oxide of
Answer: (c) nitrogen
11. Sewage water can be purified for recycling with the action of
(a) aquatic plants
Answer: (c) microorganisms
12. Which of the following gases contribute to the global warming?
(a) carbon monoxide
(b) sulphur dioxide
(c) carbon dioxide
(d) nitrogen dioxide
Answer: (c) carbon dioxide
Two marks questions with answers
1. What are pollutants?
Answer: Pollutants are substances, chemicals or any other thing which change the natural balance of the environment and thus cause pollution. Pollutants stimulate, initiate or terminate the vital reactions of an organism. These may also bring about changes in the organisms modifying the entire ecosystem.
Pollutants accumulate in the environment in large quantities due to human activities. The types, number and amount of pollutants increases with increase in the human population and his developmental activities.
2. What are primary pollutants?
Answer: Primary pollutants are pollutants persisting in the environment in the form they are passed into it, for example DDT. Primary pollutants are released directly from their source, e.g. oxides of carbon and sulphur from burning of fossil fuels, unburt hydrocarbons from automobiles, smoke, ash from factories, dust from various factories such as cement factories, mills, etc. Their toxicity is comparatively less.
3. What are secondary pollutants?
Answer: Secondary pollutants are pollutants which are formed by reaction amongst the primary pollutants. For example, peroxyacetyl nitrates (PAN) are formed through reaction between nitrogen oxides and hydrocarbons in the presence of sunlight. Secondary pollutants are often more harmful than primary pollutants. The enhanced effect is termed as synergism. They are not only toxic but also carcinogenic.
4. Differentiate between biodegradable and nonbiodegradable pollutants.
Answer: Biodegradable pollutants are those pollutants which are decomposed and degraded by microbes whereas in case of non biodegradable pollutants the pollutants are not decomposed by microbes. The pollutants are degraded quite rapidly in case of biodegradable pollutants as compared to non biodegradable pollutants. Biodegradable pollutants do not pile-up while non biodegradable pollutants often accumulate.
5. Differentiate between primary and secondary pollutants.
Answer: Primary air pollutants are air pollutants which enter air directly from the source while secondary air pollutants are air pollutants which develop from interaction of primary pollutants and atmospheric constituents. Photochemical reactions do not occur in their formation while secondary pollutants are formed through photochemical reactions that release nascent oxygen.
Three marks questions with answers
1. What are biodegradable pollutants and non-biodegradable pollutants?
Answer: Domestic sewage, cloth, paper, wood etc., come under the category of biodegradable pollutants as they can be decomposed by microorganisms. However, the decomposition becomes difficult when such materials accumulate in large quantities.
Non degradable pollutants- Aluminium cans, articles made of plastic, compounds of mercury, DDT, glass etc., are non degradable waste materials. These are neither decomposed by micro organisms nor do these materials break down by physical and chemical agents present in the environment. There is no treatment in nature for their recycling. Therefore these continue to accumulate and occupy large useful space on the earth.
2. Mention the importance of pollutants.
Answer: Biodegradable pollutants provide energy in the form of organic substances and also nutrients like carbonate phosphate etc. The productivity of ecosystem continues to increase till the amount of such substances is moderate. When the amount reaches a certain critical limit the activities in the ecosystem show severe fluctuations. If these pollutants are added to the ecosystem even beyond this critical limit, the balance is completely lost and it becomes disturbed. Non degradable pollutant, not only accumulates in the ecosystem but pass from one organism of the food chain to another till it reaches the last trophic level. During this transport the amount of the pollutant continues to increase with each trophic level. This is termed as biomagnification. The pollutants form toxic substances in combination with other substances when it passes through different trophic levels. Such substances are harmful and even kill the biotic components.
3. List some harmful effects of pollutants
Answer: Following are some of the major harmful effects
(1) Loss of raw materials
(2) Unnecessary expenditure on pollution control.
(3) Health hazards due to pollution related diseases such as asthma, cancer etc.
(4) Increase in the death rate.
(5) Decrease in the working efficiency of man.
(6) Damage to the crops.
(7) Damage to the buildings, metals, paints, varnishes, cloth etc.
(8) Environment of the earth becomes progressively unfit for living.
4. List some of the major pollutants
Answer: Following are some of the major pollutants:
- Gases such as carbon monoxide, sulphur dioxide, hydrogen sulphide, oxides nitrogen and halogens (i.e., chlorine bromine Iodine) etc.
- Particulate matter,e.g., dust, soot, grit,etc.
- Acid droplets of sulphuric and nitric acid.
- Metals like chromium, lead, zinc, mercury, nickel, cadmium,etc.
- Agro Chemicals such as insecticides, herbicides, weedicides, pesticides,etc.
- Organic substances such as benzene, benzpyrene, alkyl benzene sulphonates (ABS), etc.
- Photochemical oxidants,e.g., ozone, peroxyacetyl nitrate (PAN), ethylene,etc.
- Radioactive substances like uranium, plutonium, strontium iodine etc.