NCERT Exemplar solutions for Chemistry [English] Class 11 chapter 14 - Environmental Chemistry [Latest edition]

Which of the following gases is not a green house gas?

Photochemical smog occurs in warm, dry and sunny climate. One of the following is not amongst the components of photochemical smog, identify it.

Which of the following statements is not true about classical smog?

Biochemical Oxygen Demand, (BOD) is a measure of organic material present in water. BOD value less than 5 ppm indicates a water sample to be ______.

Which of the following statements is wrong?

Sewage containing organic waste should not be disposed in water bodies because it causes major water pollution. Fishes in such a polluted water die because of ______.

Which of the following statements about photochemical smog is wrong?

The gaseous envelope around the earth is known as atmosphere. The lowest layer of this is extended upto 10 km from sea level, this layer is ______.

Dinitrogen and dioxygen are main constituents of air but these do not react with each other to form oxides of nitrogen because ______.

The pollutants which come directly in the air from sources are called primary pollutants. Primary pollutants are sometimes converted into secondary pollutants. Which of the following belongs to secondary air pollutants?

Which of the following statements is correct?

Which of the following practices will not come under green chemistry?

Which of the following conditions shows the polluted environment.

(i) pH of rain water is 5.6.

(ii) amount of carbondioxide in the atmosphere is 0.03%.

(iii) biochemical oxygen demand 10 ppm.

(iv) eutrophication.

Phosphate containing fertilisers cause water pollution. Addition of such compounds in water bodies causes:

(i) enhanced growth of algae.

(ii) decrease in amount of dissolved oxygen in water.

(iii) deposition of calcium phosphate.

(iv) increase in fish population.

The acids present in acid rain are:

(i) Peroxyacetylnitrate

(ii) H₂CO₃ 

(iii) HNO₃

(iv) H₂SO₄ 

The consequences of global warming may be:

(i) increase in average temperature of the earth.

(ii) melting of Himalayan Glaciers.

(iii) increased biochemical oxygen demand.

(iv) eutrophication.

Green house effect leads to global warming. Which substances are responsible for green house effect?

Acid rain is known to contain some acids. Name these acids and where from they come in rain?

Ozone is a toxic gas and is a strong oxidising agent even then its presence in the stratosphere is very important. Explain what would happen if ozone from this region is completely removed?

Dissolved oxygen in water is very important for aquatic life. What processes are responsible for the reduction of dissolved oxygen in water?

On the basis of chemical reactions involved, explain how do chlorofluorocarbons cause thinning of ozone layer in stratosphere.

What could be the harmful effects of improper management of industrial and domestic solid waste in a city?

During an educational trip, a student of botany saw a beautiful lake in a village. She collected many plants from that area. She noticed that villagers were washing clothes around the lake and at some places waste material from houses was destroying its beauty. After few years, she visited the same lake again. She was surprised to find that the lake was covered with algae, stinking smell was coming out and its water had become unusable. Can you explain the reason for this condition of the lake?

What are biodegradable and non-biodegradable pollutants?

What are the sources of dissolved oxygen in water?

What is the importance of measuring BOD of a water body?

Why does water covered with excessive algal growth become polluted?

A factory was started near a village. Suddenly villagers started feeling the presence of irritating vapours in the village and cases of headache, chest pain, cough, dryness of throat and breathing problems increased. Villagers blamed the emissions from the chimney of the factory for such problems. Explain what could have happened. Give chemical reactions for the support of your explanation.

Oxidation of sulphur dioxide into sulphur trioxide in the absence of a catalyst is a slow process but this oxidation occurs easily in the atmosphere. Explain how does this happen. Give chemical reactions for the conversion of SO₂ into SO₃.

From where does ozone come in the photochemical smog?

How is ozone produced in stratosphere?

Ozone is a gas heavier than air. Why does ozone layer not settle down near the earth?

Some time ago formation of polar stratospheric clouds was reported over Antarctica. Why were these formed? What happens when such clouds break up by warmth of sunlight?

A person was using water supplied by Municipality. Due to shortage of water he started using underground water. He felt laxative effect. What could be the cause?

Match the terms given in Column I with the compounds given in Column II.

Match the pollutant(s) in Column I with the effect(s) in Column II.

Match the activity given in Column I with the type of pollution created by it given in Column II.

Match the pollutants given in Column I with their effects given in Column II.

Assertion (A): Green house effect was observed in houses used to grow plants and these are made of green glass.

Reason (R): Green house name has been given because glass houses are made of green glass.

Assertion (A): The pH of acid rain is less than 5.6.

Reason (R): Carbon dioxide present in the atmosphere dissolves in rain water and forms carbonic acid.

Assertion (A): Photochemical smog is oxidising in nature.

Reason (R): Photochemical smog contains NO₂ and O₃, which are formed during the sequence of reactions.

Assertion (A): Carbon dioxide is one of the important greenhouse gases.

Reason (R): It is largely produced by respiratory function of animals and plants.

Assertion (A): Ozone is destroyed by solar radiation in upper stratosphere.

Reason (R): Thinning of the ozone layer allows excessive UV radiations to reach the surface of earth.

Assertion (A): Excessive use of chlorinated pesticide causes soil and water pollution.

Reason (R): Such pesticides are non-biodegradable.

Assertion (A): If BOD level of water in a reservoir is less than 5 ppm it is highly polluted.

Reason (R): High biological oxygen demand means low activity of bacteria in water.

How can you apply green chemistry for the following:

To control photochemical smog.

How can you apply green chemistry for the following:

To avoid use of halogenated solvents in drycleaning and that of chlorine in bleaching.

How can you apply green chemistry for the following:

To reduce use of synthetic detergents.

How can you apply green chemistry for the following:

To reduce the consumption of petrol and diesel.

Green plants use carbon dioxide for photosynthesis and return oxygen to the atmosphere, even then carbon dioxide is considered to be responsible for greenhouse effect. Explain why?

Explain how does greenhouse effect cause global warming.

A farmer was using pesticides on his farm. He used the produce of his farm as food for rearing fishes. He was told that fishes were not fit for human consumption because large amount of pesticides had accumulated in the tissues of fishes. Explain how did this happen?

For dry cleaning, in the place of tetrachloroethane, liquefied carbon dioxide with suitable detergent is an alternative solvent. What type of harm to the environment will be prevented by stopping use of tetrachloroethane? Will use of liquefied carbon dioxide with detergent be completely safe from the point of view of pollution? Explain.