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प्रश्न
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?
उत्तर
In summer season, nitrogen dioxide and methane react with chlorine monoxide and chlorine atoms forming chlorine sinks, preventing much ozone depletion, whereas in winter, special type of clouds called polar stratospheric clouds are formed over Antarctica. These polar stratospheric clouds provide surface on which chlorine nitrate gets hydrolysed to form hypochlorous acid. It also reacts with hydrogen chloride to give molecular chlorine.
\[\ce{ClO (g) + NO2 -> ClONO (g)}\]
\[\ce{Cl (g) + CH4 (g) -> CH3 (g) + HCl (g)}\]
\[\ce{ClONO2 (g) + H2O (g) -> HOCl (g) + H2O3}\]
\[\ce{CLONO2 (g) + HCL (g) -> Cl2 (g) + HNO3 (g)}\]
When sunlight returns to the Antarctica in spring, the sun’s warmth breaks up the clouds and HOCl, Cl2 are photolysed by sunlight.
\[\ce{HOCl (g) ->[hv] OH (g) + Cl (g)}\]
\[\ce{Cl2 (g) ->[hv] 2Cl (g)}\]
The chlorine radicals thus formed initiate the chain reaction for ozone depletion.
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संबंधित प्रश्न
Explain tropospheric pollution in 100 words.
Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?
What would have happened if the greenhouse gases were totally missing in the earth’s atmosphere? Discuss.
Which of the following gases is not a green house gas?
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 ______.
Match the terms given in Column I with the compounds given in Column II.
| Column I | Column II |
| (i) Acid rain | (a) CHCl2 – CHF2 |
| (ii) Photochemical smog | (b) CO |
| (iii) Combination with haemoglobin | (c) CO2 |
| (iv) Depletion of ozone layer | (d) SO2 |
| (e) Unsaturated hydrocarbons |
Match the pollutant(s) in Column I with the effect(s) in Column II.
| Column I | Column II |
| (i) Oxides of sulphur | (a) Global warming |
| (ii) Nitrogen dioxide | (b) Damage to kidney |
| (iii) Carbon dioxide | (c) ‘Blue baby’ syndrome |
| (iv) Nitrate in drinking water | (d) Respiratory diseases |
| (v) Lead | (e) Red haze in traffic and congested areas |
Match the pollutants given in Column I with their effects given in Column II.
| Column I | Column II |
| (i) Phosphate fertilisers in water | (a) BOD level of water increases |
| (ii) Methane in air | (b) Acid rain |
| (iii) Synthetic detergents in water | (c) Global warming |
| (iv) Nitrogen oxides in air | (d) Eutrophication |
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.
Match List - I with List - II.
| List - I | List - II | ||
|
(a) |
\[\ce{2SO2(g) + O2(g) -> 2SO3(g)}\] | (i) | Acid rain |
| (b) | \[\ce{HOCl(g) ->[hv] \overset{\bullet}{O}H + \overset{\bullet}{C}l}\] | (ii) | Smog |
| (c) | \[\ce{CaCO3 + H2SO4 -> CaSO4 + H2O + CO2}\] | (iii) | Ozone depletion |
| (d) | \[\ce{NO2(g) ->[hv] NO(g) + O(g)}\] | (iv) | Tropospheric pollution |
Choose the correct answer from the options given below.
