Problem 69
About \(20 \mathrm{~km}\) above the earth there is an ozone layer. Which of the following statements about ozone and ozone layer are false? (1) The conversion of ozone to oxygen is an endothermic reaction. (2) Ozone layer is beneficial to us because ozone cuts out the ultraviolet radiation of the sun. (3) Ozone layer is harmful to us because it cuts off radiations useful for photosynthesis. (4) Ozone has a triatomic linear molecule. (a) 1,2 and 3 (b) 1,3 and 4 (c) 2,3 and 4 (d) 3 and 4 only
Problem 70
Ozone is formed in the upper layer of the atmosphere from oxygen by the action of (a) cosmic rays (b) ultraviolet rays (c) free radicals (d) nitrogen oxides
Problem 71
Pick up the incorrect statements here. (1) Classical smog is good for health but not photochemical smog. (2) During formation of smog the level of ozone in the atmosphere goes down. (3) Classical smog has an oxidizing character while the photochemical smog is reducing in character. (4) Photochemical smog occurs in day time whereas the classical smog occurs in early morning hours. (a) 1,2 and 3 (b) 1,3 and 4 (c) 2 and 3 only (d) 3 and 4 only
Problem 72
Which statements are correct here? (1) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) particulates have size of \(500-1000 \mathrm{~nm}\). (2) Soot particles have a diameter of about \(5 \mathrm{~nm}\). (3) Fly ash particles have diameter of \(5 \times 10^{5} \mathrm{~nm}\). (a) 1 and 2 (b) 2 and 3 (c) 1 and 3 (d) 1,2 and 3
Problem 73
Use of chlorofluoro carbons is not encouraged because (a) they are harmful to the eyes of people that use it (b) they damage the refrigerators and air conditioners (c) they eat away the ozone in the atmosphere (d) they destroy the oxygen layer
Problem 74
Consider the following statements: (1) PAN is secondary air pollutant (2) BOD and COD values are indicators of water pollution level. Which of the statements given above is/are correct? (a) both 1 and 2 (b) 1 only (c) 2 only (d) neither 1 nor 2
Problem 75
Match the list I and list II and pick the correct matching from the codes given below. List (a) Peroxy acetyl nitrate (b) Polycyclic aromatic hydrocarbons (c) Dioxins List II 1\. Waste incineration 2\. Global warming 3\. Photochemical smog 4\. Carcinogens 5\. Vat dye (e) IR active molecules (a) a 3, b 4, c 1, d 5, e 2 (b) a \(2, \mathrm{~b} 3, \mathrm{c} 5, \mathrm{~d} 4, \mathrm{e} 1\) (c) a \(5, \mathrm{~b} 3, \mathrm{c} 1, \mathrm{~d} 2, \mathrm{e} 4\) (d) a \(1, \mathrm{~b} 2, \mathrm{c} 3, \mathrm{~d} 4, \mathrm{e} 5\)
Problem 76
When rain is accompanied by a thunderstorm, the collected rain water will have a pH value (a) which depends upon the amount of dust in the air (b) slightly lower than that of rain water without the thunderstorm (c) slightly higher than that when the thunderstorm is not here (d) uninfluenced by occurrence of thunderstorm
Problem 77
Smog is essentially caused by presence of (a) \(\mathrm{O}_{2}\) and \(\mathrm{N}_{2}\) (b) \(\mathrm{O}_{2}\) and \(\mathrm{O}_{3}\) (c) \(\mathrm{O}_{3}\) and \(\mathrm{N}_{2}\) (d) oxides of sulphur and nitrogen
Problem 78
Identify the wrong statements in the following: (a) Chlorofluorocarbons are responsible for ozone layer depletion (b) Green house effect is responsible for global warming. (c) Ozone layer does not permit infrared radiation from the sun to react the earth. (d) Acid rains is mostly because of oxides of nitrogen and sulphur.
