Q: Among the following, the one that is not a green house gas is:

FactSO2(g) is not a greenhouse gas.

Q: Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?

CO is poisionous and CO2 is non toxic in nature. CO forms complex with haemoglobin which is more stable than complex of oxygen with haemoglobin. The concentration range of 3-4 % of CO decreases the oxygen carrying capacity of blood. This causes headache, weak eyesight, nervousness and cardiovascular disorders. Higher concentration can be fatal. CO2 is harmful at very high concentration.

Q: Statues and monuments in India are affected by acid rain. How?

Chemical pollutants (gaseous oxides such as CO2,NO2 and SO2) present in the atmosphere react with water to form carbonic acid, nitric acid and sulphuric acid. This causes acid rain which corrodes marble statues and monuments. The reaction between the calcium carbonate present in the monoumnets and the acid of acid rain is given below.CO2+H2O→ CaCO3 or Ca(HCO3)2 CaCO3+H2SO4→CaSO4+CO2+H2OThe products are water soluble and washed away. The presence of carbonate, sulphate and nitrate salts causes blackening of marble surfaces.

Question 1

Among the following, the one that is not a green house gas is:

Accepted Answer

FactSO2​(g)  is not a greenhouse gas.

Question 2

Which oxide of nitrogen is not a common pollutant introduced into the atmosphere both due to natural and human activity?

Accepted Answer

Fact

Question 3

Which of the following is not a common component of Photochemical Smog?

Accepted Answer

The common components of photochemical smog are ozone, nitric oxide, ocrolein, for malde nyde and peroxyacehyl nitrate (PAN).Hence FC is not common component of photochemical smog.

Question 4

Define environmental chemistry.

Accepted Answer

Environmental chemistry is the study of chemical and biochemical processes as occurring in nature. It deals with the study of origin, transport, reaction, effects and fates of various chemical species in the environment.

Question 5

Explain tropospheric pollution in 100 words.

Accepted Answer

The presence of unwanted substances in the lowest layer of the atmosphere results in tropospheric pollution. Major gaseous pollutants include oxides of sulphur, nitrogen, carbon and hydrocarbons.Burning of fossil fuels (coal, automobile fuel) produce oxides of sulphur and nitrogen. They react with water in presence of oxygen of air and form nitric acid and sulphuric acid. This causes acid rain which is harmful to agriculture plants and trees. It causes various respiratory ailments.Burning of hydrocarbons (carcinogens) produce oxides of carbon. CO is poisonous and can lead to death. CO2​ is responsible for global warming. Particulates of smoke dust mist and fume are harmful for human health and cause respiratory ailments.

Question 6

Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?

Accepted Answer

CO is poisionous and CO2​ is non toxic in nature. CO forms complex with haemoglobin which is more stable than complex of oxygen with haemoglobin. The concentration range of 3-4 % of CO decreases the oxygen carrying capacity of blood. This causes headache, weak eyesight, nervousness and cardiovascular disorders. Higher concentration can be fatal. CO2​ is harmful at very high concentration.

Question 7

List the gases which are responsible for greenhouse effect.

Accepted Answer

The gases which are responsible for the greenhouse effect:Carbon dioxide CO2​Methane CH4​Water H2​ONitrous oxide NOOzone O3​Chlorofluorocarbons CFCs

Question 8

Statues and monuments in India are affected by acid rain. How?

Accepted Answer

Chemical pollutants (gaseous oxides such as CO2​,NO2​  and SO2​) present in the atmosphere react with water to form carbonic acid, nitric acid and sulphuric acid. This causes acid rain which corrodes marble statues and monuments. The reaction between the calcium carbonate present in the monoumnets and the acid of acid rain is given below.CO2​+H2​O→ CaCO3​ or Ca(HCO3​)2​ CaCO3​+H2​SO4​→CaSO4​+CO2​+H2​OThe products are water soluble and washed away. The presence of carbonate, sulphate and nitrate salts causes blackening of marble surfaces.

Question 9

What is smog? How is classical smog different from photo chemical smog?

Accepted Answer

Smog is a type of air pollution. It is a blend of smoke and fog. Smog is classified into classical smog and photochemical smog.Classical smog occurs in a cool, humid climate. Its components include smoke, fog and sulphur dioxide. It is reducing in nature.Photochemical smog occurs in a dry, sunny climate. Its components are PAN, acrolein, ozone, formaldehyde, nitric oxide. It is oxidizing in nature.

Question 10

Write down the reactions involved during the formation of photo chemical smog.

Accepted Answer

Photochemical smog occurs in a dry, sunny climate. Its components are PAN, acrolein, ozone, formaldehyde, nitric oxide. It is oxidizing in nature.It is formed as a result of the reaction of sunlight with hydrocarbons and nitrogen oxides. The reactions involved during formation of photochemical smog are shown in the attached image.................(i)Oxygen atoms are very reactive and combine with the dioxygen to produce ozone........................(ii)It rapidly reacts with NO, formed in the first reaction and regenerate (g)Both  and ozone are oxidising in nature so they react with the unburnt hydrocarbon in the air to form PAN, formaldehyde and acrolein.

Question 11

What are the harmful effects of photochemical smog and how can they be controlled?

Accepted Answer

Harmful effects of photochemical smog:1) It corrode metals, stones, rubber and painted surface.2) It causes serious health problems to senior citizens, children and people with heart and lung problems which lead to emphysema, bronchitis, asthma.3) It causes pneumonia, inflammation of pulmonary tissues, fatigue, heart palpitations, premature aging of lungs and death.Control measures:1) The release of NO2​ and hydrocarbons in the atmosphere can be prevented by using catalytic converters.2) Switching over to other types of fuels, desulfurization of fuel gases from coal fired power plants, expansion of public rail transport.3) Since plants can metabolize NO2​, Pinus, Juniparur, Quercus, Pyrus and Vitis should be planted.

Question 12

What are the reactions involved for ozone layer depletion in the stratosphere?

Accepted Answer

UV radiations act on dioxygen to form ozone.There is dynamic equilibrium between the production and decomposition of ozone. The disturbance of this equilibrium results in ozone depletion.Chlorofluorocarbons mix with atmospheric gases and reach the stratosphere, where they are decomposed by UV rays to produce chlorine free radicals.These chlorine free radicals react with ozone to form oxygen and ClO⋅ free radicals which react with atomic O to produce more chlorine free radicals.This results in continuous breakdown of ozone present in the stratosphere damaging the ozone layer.

Question 13

What do you mean by ozone hole? What are its consequences?

Accepted Answer

The ozone hole is the depletion of the ozone layer. The ozone layer absorbs the harmful UV rays coming from the sun and therefore does not allow those rays to reach Earth's surface. Consequences of ozone depletion:Due to its depletion, more radiation enters the Earth's atmosphere. UV radiations cause ageing of the skin, cataracts, skin cancer, and sunburns. Hence, they are harmful. They cause the death of phytoplanktons which leads to a decrease in fish productivity. Excess exposure may even cause mutation in the genetic material of organisms.

Question 14

What are the major causes of water pollution? Explain.

Accepted Answer

Several human activities leads to presence of several undesirable substances in water which causes water pollution.  Various sources of different water pollutants are shown below. Pollutant Source Micro-organisms Domestic sewage Organic wastes Domestic sewage, decaying animals and plants, animal excreta and waste, discharge from food processing industries. Plant nutrients Chemical fertilizers Toxic heavy metals Chemical factories and industries Sediments Strip mining and soil erosion Pesticides Chemical used for killing fungi, weed, insects Radioactive substances Mining of uranium-containing minerals Heat Water used for cooling in industries.

Question 15

Have you ever observed any water pollution in your area? What measures would you suggest to control it ?

Accepted Answer

Various human activities causes water pollution. They include discharges from wastewater treatment plants, run-off from agricultural fields, storm water drainage etc. Pollutants contaminate water bodies.Chemical factories and various industries discharge toxic heavy melts such as Fe, Mn, Al and organic wastes into water.Domestic sewege and animal excreta contaminate water.All industrial and chemical discharges should be free from toxic metals before allowing them to enter water bodies. There should be regular checks for the concentration of these species. To prevent harmful chemicals from entering ground water, compost should be used instead of chemical fertilizers in gardens and agricultural fields.

Question 16

What do you mean by Biochemical Oxygen Demand (BOD)?

Accepted Answer

The amount of dissolved oxygen needed by aerobic biological organisms in a body of water to breakdown organic material present in a given water sample at certain temperature over a specific time period is called BOD.

Question 17

Do you observe any soil pollution in your neighbourhood? What efforts will you make for controlling the soil pollution?

Accepted Answer

Industrial wastes and agricultural pollutants such as pesticides, fertilizers etc are major sources of soil pollution.The quality and fertility of soils should be maintained to ensure and sustain the growth of plants and food crops.DDT is water insoluble. Hence, DDT (and other such insecticides) remain in soil for a long time and contaminate the root crops. Pesticides such as Aldrin and Dieldrin are non biodegradable and highly toxic in nature. They can enter the higher trophic levels through food chains, causing metabolic and physiological disorders. The same is true for industrial wastes that comprises of several toxic metals such as Pb, As, Hg, Cd etc.Control measures :The addition of pollutants to the soil should be avoided. Also, proper treatment should be given to wastes. They should first be recycled and then dumped.

Question 18

What are pesticides and herbicides? Explain with examples.

Accepted Answer

A mixture of two or more substances used for killing pests are called pesticides. pests include insects, plant pathogens, weeds, mollusks, etc, that destroy the plant crop and spread diseases. Aldrin and dieldrin are the names of some common pesticides.Herbicides are pesticides specially meant for killing weeds. Examples include sodium chlroride (NaClO3​), sodium arsenite (Na3​AsO3​) etc.

Question 19

What do you mean by green chemistry? How will it help decrease environmental pollution?

Accepted Answer

Green chemistry is a production process that aims at using the existing knowledge and principles of chemistry for developing and implementing chemical products and processes to reduce the use and generation of substances hazardous to the environment.The philosophy of encouraging the design of products and processes that reduce or eliminate the use and generation of hazardous substances. Green chemistry seeks to reduce and prevent pollution at its source and can, therefore, play a major role in decreasing the environmental pollution.

Question 20

What would have happened if the green house gases were totally missing in the earth's atmosphere? Discuss.

Accepted Answer

Following gases are responsible for green house effect.Carbon dioxide CO2​Methane CH4​Water H2​ONitrous oxide NOOzone O3​Chlorofluorocarbons CFCsThey are present near earth's surface. They absorb solar energy radiated back from the earth surface.Due to this, the atmosphere is heated. Thus, these gases are essential for maintaining the temperature of earth for the sustenance of life.In the absence of green house gases, there will be significant decrease in the average temperature of earth. Due to this, life will not be possible on earth.

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Solution for Class 11, Chemistry, Environmental Chemistry

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