Ncert Solutions Chemistry Class 11th

This is a Short answer type Questions as classified in NCERT Exemplar

Ozone is found to be thermodynamically unstable and undergoes decomposition into molecular oxygen and a dynamic equilibrium exists between the production and decomposition of ozone. The reactions involved can be shown as- 

O₂ (g)  O (g) + O (g)

O (g) + O₂ (g) +M O₃ (g) + M

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (i) the reaction is endothermic and requires very high temperature is correct since dinitrogen and dioxygen are the main constituents of air. These gases do not react with each other at a normal temperature. The dissociation energy of N₂is very high due to the presence of triple bond and it is very stable. 

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (ii) Troposphere is correct since the lowest region of atmosphere in which the human beings along with other organisms live is called troposphere. It extends up to the height of  approximately 10 km from sea level. 

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (ii) i.e., It has low concentration of oxidizing agents is the answer since the common components of photochemical smog are ozone, nitric oxide, acrolein, formaldehyde and peroxyacetyl nitrate (PAN). Photochemical smog causes serious health problems and both ozone and PAN act as powerful eye irritants. Photochemical smog contains high concentrations of oxidants. 

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (iii)

i.e., Decrease in the amount of dissolved oxygen in water is the answer since organic waste is oxidized by microorganisms in the presence of dissolved oxygen. Hence, oxygen decreases in water as a result it is harmful for aquatic life. 

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (i)

i.e., Its main components are produced by the action of sunlight on emissions of automobiles and factories is the answer since classical smog is a mixture of smoke, fog and sulphur dioxide and occurs in cold humid climates. While the gases released by automobiles and factories are not responsible for classical fog. 

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (iii)

SO₂ is correct since photochemical fog is formed in the presence of sunlight in summers when NO and hydrocarbons are present in large amounts in the atmosphere. SO₂ is not responsible for photochemical fog. 

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (i)

CO is correct since it does not absorb sunlight near the earth's surface and hence it is not radiated back to the earth. Greenhouse gases have this kind of property.