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
The total amount of oxygen consumed by micro-organisms (bacteria) in decomposing organic matter present in certain volume of a sample of water is called Biochemical Oxygen Demand (BOD) of the water.
Water is considered to be pure if it has BOD less than 5 ppm, whereas highly polluted water has BOD more than 17 ppm. Thus, the water having BOD less than 5 ppm is rich in dissolved oxygen.
Ozone is a toxic gas and is a strong oxidizing agent, even then its presence in the stratosphere is very important. Explain what would happen if ozone from this region is completely removed.
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?
What would have happened if the greenhouse gases were totally missing in the earth’s atmosphere? Discuss.
Assertion (A): Carbon dioxide is one of the important greenhouse gases. Reason (R): It is largely produced by respiratory function of animals and plants.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) Both A and R are not correct.
(d) A is not correct but R is correct.
Oxidation of 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 S02 into S03.
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.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) Both A and R are not correct.
(d) A is not correct but R is correct.
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.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) Both A and R are not correct.
(d) A is not correct but R is correct.
On the basis of chemical reactions involved, explain how do chlorofluoro- carbons cause thinning of ozone layer in stratosphere.
Assertion (A): Photochemical smog is oxidizing in nature.
Reason (R): Photochemical smog contains N02 and 03, which are formed during the sequence of reactions.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) Both A and R are not correct.
(d) A is not correct but R is correct.
What do you mean by green chemistry? How will it help in decreasing environmental pollution ?
Match the terms given in Column I with the compounds given in Column
| Column 1 | Column II | ||
| (a) | Acid rain | (1) | CHC12-CHF2 |
| (b) | Photochemical smog | (2) | CO |
| (c) | Combination with haemoglobin | (3) | co2 |
| (d) | Depletion of ozone layer | (4) | so2 |
| (5) | Unsaturated hydrocarbons | ||
Acid rain is known to contain some acids. Name these acids. From where do they come in rain?
What could be the harmful effects of improper management of industrial and domestic solid waste in a city?
Assertion (A): Excessive use of chlorinated synthetic pesticides causes soil and water pollution.
Reason (R): Such pesticides are non-biodegradable.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) Both A and R are not correct.
(d) A is not correct but R is correct.
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 r 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?
(a) Define eutrophication and pneumoconiosis.
(b) Write difference between photochemical and 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 correct?
(a) Ozone hole is a hole formed in stratosphere from which ozone oozes out.
(b) Ozone hole is a hole formed in the troposphere from which ozone oozes out. .
(c) Ozone hole is thinning of ozone layer of stratosphere at some places.
(d) Ozone hole means vanishing of ozone layer around the earth completely.
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.
Match the pollutants given in Column I with their effects given in Column II.
(a) Sulphur dioxide causes classical smog, acid rain, water pollution, induces breathing problems, causes damage to buildings, corrosion of metals.
(b) Using carbamates as pesticides can cause nerve diseases in humans
(c) Using synthetic detergents for washing clothes causes water pollution.
(d) Unsaturated hydrocarbons and nitrogen oxides produced by automobiles and factories cause photochemical smog, damage to plant life, corrosion to building material, induce breathing problems, water pollution.
(e) Chlorofluorocarbons are believed to be the main reason for ozone layer depletion.
| Column I | Column II | ||
| (a) | Phosphate fertilizers in water | (1) | BOD level of water increases |
| (b) | Methane in air | (2) | Acid rain |
| (c) | Synthetic detergents in water | (3) | Global warming |
| (d) | Nitrogen oxides in air | (4) | Eutrophication |