Atmospheric Pollution — Troposphere and Stratosphere - UNSOLVED PRACTICE SET

Q7. Differentiate between the troposphere and the stratosphere with respect to:

(a) Temperature variation with altitude

(b) Major chemical species present

Q8. What is temperature inversion? How does it worsen air pollution in cities like Delhi during winter?

Q9. Why is ozone beneficial in the stratosphere but harmful in the troposphere?

Q10. Name the major pollutants found in the troposphere and their primary sources.

Q11. Your school is located near a busy road in Mumbai. During morning assembly, you notice a brownish haze. Explain what this haze is and which atmospheric layer it belongs to.

Q12. Why does the stratosphere have a higher temperature than the upper troposphere, despite being farther from the Earth's surface?

Q13. Discuss the structure and composition of the atmosphere with emphasis on the troposphere and stratosphere:

(a) Layers of the atmosphere and their approximate altitudes

(b) Temperature profile in each layer

(c) Major gases and their approximate percentages in the troposphere

(d) The role of the tropopause as a boundary between troposphere and stratosphere

(e) Why the stratosphere is called the "ozonosphere"

Q14. Explain tropospheric pollution in detail:

(a) Major pollutants — oxides of sulphur and nitrogen, carbon monoxide, hydrocarbons, particulate matter

(b) Sources of these pollutants in Indian cities

(c) Formation of photochemical smog — role of NOₓ and hydrocarbons in sunlight

(d) The phenomenon of temperature inversion and its role in trapping pollutants (winter smog in Delhi)

(e) Health effects of tropospheric pollution

Q15. The atmosphere over Indian cities is severely polluted, especially during winter. Discuss:

(a) Why Delhi experiences severe smog every November (stubble burning, vehicular emissions, firecrackers, meteorological conditions)

(b) The role of the Indo-Gangetic Plain's geography in trapping pollutants

(c) How the stratosphere over India is affected by the Asian monsoon system

(d) Satellite data showing pollution plumes over major Indian cities and their cross-border movement

Q16. The concentration of various gases in the troposphere at sea level is:

N₂: 780,840 ppm

O₂: 209,460 ppm

Ar: 9,340 ppm

CO₂: 420 ppm

(a) Convert the CO₂ concentration from ppm to percentage.

(b) If the total mass of the atmosphere is 5.15 × 10¹⁸ kg, calculate the mass of CO₂ in the atmosphere.

(c) If CO₂ increases by 2.5 ppm per year, calculate how many years it will take to reach 500 ppm.

Q17. A thermal power plant in Uttar Pradesh emits flue gas at 150°C containing:

SO₂: 500 ppm

NOₓ: 200 ppm

CO: 50 ppm

(a) Calculate the mass of SO₂ emitted per hour if the plant releases 100,000 m³ of flue gas per hour at STP.

(b) If an electrostatic precipitator removes 95% of particulate matter, and the initial concentration is 500 mg/m³, calculate the final concentration.

(c) The plume rises to 500 m altitude where temperature inversion occurs at 20°C. Calculate the temperature at the ground if the normal lapse rate is 6.5°C/km and the inversion layer starts at 300 m.

Q18. The ozone concentration in the stratosphere peaks at about 25 km altitude with a maximum concentration of 10 ppm.

(a) If the total pressure at 25 km is 40 mbar, calculate the partial pressure of ozone.

(b) The ozone layer absorbs 98% of UV-C radiation (200-280 nm). If the incident UV-C flux is 10 W/m², calculate the absorbed energy per m².

(c) If CFCs deplete ozone at a rate of 3% per decade, calculate the ozone concentration after 30 years if no action is taken.